==================================================================
BUG: KASAN: use-after-free in ext4_ext_binsearch fs/ext4/extents.c:841 [inline]
BUG: KASAN: use-after-free in ext4_find_extent+0xa36/0xa70 fs/ext4/extents.c:956
Read of size 4 at addr ffff8880126e18cc by task kworker/u8:8/25406

CPU: 1 UID: 0 PID: 25406 Comm: kworker/u8:8 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: writeback wb_workfn (flush-7:9)
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xcd/0x630 mm/kasan/report.c:482
 kasan_report+0xe0/0x110 mm/kasan/report.c:595
 ext4_ext_binsearch fs/ext4/extents.c:841 [inline]
 ext4_find_extent+0xa36/0xa70 fs/ext4/extents.c:956
 ext4_ext_map_blocks+0x290/0x5fe0 fs/ext4/extents.c:4208
 ext4_map_create_blocks fs/ext4/inode.c:609 [inline]
 ext4_map_blocks+0x570/0x1400 fs/ext4/inode.c:811
 mpage_map_one_extent fs/ext4/inode.c:2374 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2468 [inline]
 ext4_do_writepages+0x1ffa/0x3cf0 fs/ext4/inode.c:2931
 ext4_writepages+0x37a/0x7d0 fs/ext4/inode.c:3025
 do_writepages+0x27a/0x600 mm/page-writeback.c:2634
 __writeback_single_inode+0x160/0xfb0 fs/fs-writeback.c:1680
 writeback_sb_inodes+0x60d/0xfa0 fs/fs-writeback.c:1976
 wb_writeback+0x419/0xb70 fs/fs-writeback.c:2156
 wb_do_writeback fs/fs-writeback.c:2303 [inline]
 wb_workfn+0x14d/0xbe0 fs/fs-writeback.c:2343
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3236
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x26f pfn:0x126e1
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea0002e16508 ffffea000049b808 0000000000000000
raw: 000000000000026f 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 317, tgid 315 (syz.8.8411), ts 2513579614652, free_ts 2514677893529
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1851
 prep_new_page mm/page_alloc.c:1859 [inline]
 get_page_from_freelist+0x132b/0x38e0 mm/page_alloc.c:3858
 __alloc_frozen_pages_noprof+0x261/0x23f0 mm/page_alloc.c:5148
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2416
 folio_alloc_mpol_noprof+0x36/0x2f0 mm/mempolicy.c:2435
 shmem_alloc_folio+0x135/0x160 mm/shmem.c:1908
 shmem_alloc_and_add_folio+0x499/0xc20 mm/shmem.c:1947
 shmem_get_folio_gfp+0x67f/0x1600 mm/shmem.c:2597
 shmem_fault+0x1fe/0xa30 mm/shmem.c:2798
 __do_fault+0x10d/0x490 mm/memory.c:5152
 do_read_fault mm/memory.c:5573 [inline]
 do_fault mm/memory.c:5707 [inline]
 do_pte_missing+0xf50/0x3ba0 mm/memory.c:4234
 handle_pte_fault mm/memory.c:6052 [inline]
 __handle_mm_fault+0x152a/0x2a50 mm/memory.c:6195
 handle_mm_fault+0x589/0xd10 mm/memory.c:6364
 faultin_page mm/gup.c:1144 [inline]
 __get_user_pages+0x551/0x34a0 mm/gup.c:1446
 populate_vma_page_range+0x267/0x3f0 mm/gup.c:1880
 __mm_populate+0x1d8/0x380 mm/gup.c:1983
page last free pid 323 tgid 315 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1395 [inline]
 free_unref_folios+0xa61/0x16b0 mm/page_alloc.c:2952
 folios_put_refs+0x56f/0x740 mm/swap.c:997
 folio_batch_release include/linux/pagevec.h:101 [inline]
 shmem_undo_range+0x58f/0x1150 mm/shmem.c:1157
 shmem_truncate_range mm/shmem.c:1269 [inline]
 shmem_evict_inode+0x3a1/0xbe0 mm/shmem.c:1397
 evict+0x3e6/0x920 fs/inode.c:810
 iput_final fs/inode.c:1897 [inline]
 iput fs/inode.c:1923 [inline]
 iput+0x521/0x880 fs/inode.c:1909
 dentry_unlink_inode+0x29c/0x480 fs/dcache.c:466
 __dentry_kill+0x1d0/0x600 fs/dcache.c:669
 dput.part.0+0x4b1/0x9b0 fs/dcache.c:911
 dput+0x1f/0x30 fs/dcache.c:901
 __fput+0x51c/0xb70 fs/file_table.c:476
 task_work_run+0x150/0x240 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x86f/0x2bf0 kernel/exit.c:961
 do_group_exit+0xd3/0x2a0 kernel/exit.c:1102
 get_signal+0x2673/0x26d0 kernel/signal.c:3034
 arch_do_signal_or_restart+0x8f/0x7d0 arch/x86/kernel/signal.c:337

Memory state around the buggy address:
 ffff8880126e1780: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880126e1800: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8880126e1880: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                              ^
 ffff8880126e1900: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880126e1980: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
==================================================================
BUG: KASAN: use-after-free in ext4_ext_binsearch fs/ext4/extents.c:841 [inline]
BUG: KASAN: use-after-free in ext4_find_extent+0xa36/0xa70 fs/ext4/extents.c:956
Read of size 4 at addr ffff8880126e44ac by task kworker/u8:8/25406

CPU: 1 UID: 0 PID: 25406 Comm: kworker/u8:8 Tainted: G    B               syzkaller #0 PREEMPT(full) 
Tainted: [B]=BAD_PAGE
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: writeback wb_workfn (flush-7:9)
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xcd/0x630 mm/kasan/report.c:482
 kasan_report+0xe0/0x110 mm/kasan/report.c:595
 ext4_ext_binsearch fs/ext4/extents.c:841 [inline]
 ext4_find_extent+0xa36/0xa70 fs/ext4/extents.c:956
 ext4_ext_map_blocks+0x290/0x5fe0 fs/ext4/extents.c:4208
 ext4_map_create_blocks fs/ext4/inode.c:609 [inline]
 ext4_map_blocks+0x570/0x1400 fs/ext4/inode.c:811
 mpage_map_one_extent fs/ext4/inode.c:2374 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2468 [inline]
 ext4_do_writepages+0x1ffa/0x3cf0 fs/ext4/inode.c:2931
 ext4_writepages+0x37a/0x7d0 fs/ext4/inode.c:3025
 do_writepages+0x27a/0x600 mm/page-writeback.c:2634
 __writeback_single_inode+0x160/0xfb0 fs/fs-writeback.c:1680
 writeback_sb_inodes+0x60d/0xfa0 fs/fs-writeback.c:1976
 wb_writeback+0x419/0xb70 fs/fs-writeback.c:2156
 wb_do_writeback fs/fs-writeback.c:2303 [inline]
 wb_workfn+0x14d/0xbe0 fs/fs-writeback.c:2343
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3236
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x3e5 pfn:0x126e4
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f0(buddy)
raw: 00fff00000000000 ffffea0001d8ce08 ffffea00012f0088 0000000000000000
raw: 00000000000003e5 0000000000000000 00000000f0000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 303, tgid 302 (syz.7.8407), ts 2513523256396, free_ts 2516257273897
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1851
 prep_new_page mm/page_alloc.c:1859 [inline]
 get_page_from_freelist+0x132b/0x38e0 mm/page_alloc.c:3858
 __alloc_frozen_pages_noprof+0x261/0x23f0 mm/page_alloc.c:5148
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2416
 folio_alloc_mpol_noprof+0x36/0x2f0 mm/mempolicy.c:2435
 shmem_alloc_folio+0x135/0x160 mm/shmem.c:1908
 shmem_alloc_and_add_folio+0x499/0xc20 mm/shmem.c:1947
 shmem_get_folio_gfp+0x67f/0x1600 mm/shmem.c:2597
 shmem_fault+0x1fe/0xa30 mm/shmem.c:2798
 __do_fault+0x10d/0x490 mm/memory.c:5152
 do_read_fault mm/memory.c:5573 [inline]
 do_fault mm/memory.c:5707 [inline]
 do_pte_missing+0xf50/0x3ba0 mm/memory.c:4234
 handle_pte_fault mm/memory.c:6052 [inline]
 __handle_mm_fault+0x152a/0x2a50 mm/memory.c:6195
 handle_mm_fault+0x589/0xd10 mm/memory.c:6364
 faultin_page mm/gup.c:1144 [inline]
 __get_user_pages+0x551/0x34a0 mm/gup.c:1446
 populate_vma_page_range+0x267/0x3f0 mm/gup.c:1880
 __mm_populate+0x1d8/0x380 mm/gup.c:1983
page last free pid 303 tgid 302 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1395 [inline]
 free_unref_folios+0xa61/0x16b0 mm/page_alloc.c:2952
 folios_put_refs+0x56f/0x740 mm/swap.c:997
 folio_batch_release include/linux/pagevec.h:101 [inline]
 shmem_undo_range+0x58f/0x1150 mm/shmem.c:1157
 shmem_truncate_range mm/shmem.c:1269 [inline]
 shmem_evict_inode+0x3a1/0xbe0 mm/shmem.c:1397
 evict+0x3e6/0x920 fs/inode.c:810
 iput_final fs/inode.c:1897 [inline]
 iput fs/inode.c:1923 [inline]
 iput+0x521/0x880 fs/inode.c:1909
 dentry_unlink_inode+0x29c/0x480 fs/dcache.c:466
 __dentry_kill+0x1d0/0x600 fs/dcache.c:669
 dput.part.0+0x4b1/0x9b0 fs/dcache.c:911
 dput+0x1f/0x30 fs/dcache.c:901
 __fput+0x51c/0xb70 fs/file_table.c:476
 task_work_run+0x150/0x240 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x86f/0x2bf0 kernel/exit.c:961
 do_group_exit+0xd3/0x2a0 kernel/exit.c:1102
 get_signal+0x2673/0x26d0 kernel/signal.c:3034
 arch_do_signal_or_restart+0x8f/0x7d0 arch/x86/kernel/signal.c:337

Memory state around the buggy address:
 ffff8880126e4380: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880126e4400: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8880126e4480: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                  ^
 ffff8880126e4500: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880126e4580: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
==================================================================
BUG: KASAN: use-after-free in ext4_ext_binsearch fs/ext4/extents.c:841 [inline]
BUG: KASAN: use-after-free in ext4_find_extent+0xa36/0xa70 fs/ext4/extents.c:956
Read of size 4 at addr ffff8880126e4fa4 by task kworker/u8:8/25406

CPU: 0 UID: 0 PID: 25406 Comm: kworker/u8:8 Tainted: G    B               syzkaller #0 PREEMPT(full) 
Tainted: [B]=BAD_PAGE
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: writeback wb_workfn (flush-7:9)
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xcd/0x630 mm/kasan/report.c:482
 kasan_report+0xe0/0x110 mm/kasan/report.c:595
 ext4_ext_binsearch fs/ext4/extents.c:841 [inline]
 ext4_find_extent+0xa36/0xa70 fs/ext4/extents.c:956
 ext4_ext_map_blocks+0x290/0x5fe0 fs/ext4/extents.c:4208
 ext4_map_create_blocks fs/ext4/inode.c:609 [inline]
 ext4_map_blocks+0x570/0x1400 fs/ext4/inode.c:811
 mpage_map_one_extent fs/ext4/inode.c:2374 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2468 [inline]
 ext4_do_writepages+0x1ffa/0x3cf0 fs/ext4/inode.c:2931
 ext4_writepages+0x37a/0x7d0 fs/ext4/inode.c:3025
 do_writepages+0x27a/0x600 mm/page-writeback.c:2634
 __writeback_single_inode+0x160/0xfb0 fs/fs-writeback.c:1680
 writeback_sb_inodes+0x60d/0xfa0 fs/fs-writeback.c:1976
 wb_writeback+0x419/0xb70 fs/fs-writeback.c:2156
 wb_do_writeback fs/fs-writeback.c:2303 [inline]
 wb_workfn+0x14d/0xbe0 fs/fs-writeback.c:2343
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3236
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x3e5 pfn:0x126e4
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f0(buddy)
raw: 00fff00000000000 ffffea0001d8ce08 ffffea00012f0088 0000000000000000
raw: 00000000000003e5 0000000000000000 00000000f0000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 303, tgid 302 (syz.7.8407), ts 2513523256396, free_ts 2516257273897
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1851
 prep_new_page mm/page_alloc.c:1859 [inline]
 get_page_from_freelist+0x132b/0x38e0 mm/page_alloc.c:3858
 __alloc_frozen_pages_noprof+0x261/0x23f0 mm/page_alloc.c:5148
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2416
 folio_alloc_mpol_noprof+0x36/0x2f0 mm/mempolicy.c:2435
 shmem_alloc_folio+0x135/0x160 mm/shmem.c:1908
 shmem_alloc_and_add_folio+0x499/0xc20 mm/shmem.c:1947
 shmem_get_folio_gfp+0x67f/0x1600 mm/shmem.c:2597
 shmem_fault+0x1fe/0xa30 mm/shmem.c:2798
 __do_fault+0x10d/0x490 mm/memory.c:5152
 do_read_fault mm/memory.c:5573 [inline]
 do_fault mm/memory.c:5707 [inline]
 do_pte_missing+0xf50/0x3ba0 mm/memory.c:4234
 handle_pte_fault mm/memory.c:6052 [inline]
 __handle_mm_fault+0x152a/0x2a50 mm/memory.c:6195
 handle_mm_fault+0x589/0xd10 mm/memory.c:6364
 faultin_page mm/gup.c:1144 [inline]
 __get_user_pages+0x551/0x34a0 mm/gup.c:1446
 populate_vma_page_range+0x267/0x3f0 mm/gup.c:1880
 __mm_populate+0x1d8/0x380 mm/gup.c:1983
page last free pid 303 tgid 302 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1395 [inline]
 free_unref_folios+0xa61/0x16b0 mm/page_alloc.c:2952
 folios_put_refs+0x56f/0x740 mm/swap.c:997
 folio_batch_release include/linux/pagevec.h:101 [inline]
 shmem_undo_range+0x58f/0x1150 mm/shmem.c:1157
 shmem_truncate_range mm/shmem.c:1269 [inline]
 shmem_evict_inode+0x3a1/0xbe0 mm/shmem.c:1397
 evict+0x3e6/0x920 fs/inode.c:810
 iput_final fs/inode.c:1897 [inline]
 iput fs/inode.c:1923 [inline]
 iput+0x521/0x880 fs/inode.c:1909
 dentry_unlink_inode+0x29c/0x480 fs/dcache.c:466
 __dentry_kill+0x1d0/0x600 fs/dcache.c:669
 dput.part.0+0x4b1/0x9b0 fs/dcache.c:911
 dput+0x1f/0x30 fs/dcache.c:901
 __fput+0x51c/0xb70 fs/file_table.c:476
 task_work_run+0x150/0x240 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x86f/0x2bf0 kernel/exit.c:961
 do_group_exit+0xd3/0x2a0 kernel/exit.c:1102
 get_signal+0x2673/0x26d0 kernel/signal.c:3034
 arch_do_signal_or_restart+0x8f/0x7d0 arch/x86/kernel/signal.c:337

Memory state around the buggy address:
 ffff8880126e4e80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880126e4f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8880126e4f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                               ^
 ffff8880126e5000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8880126e5080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================
==================================================================
BUG: KASAN: use-after-free in ext4_ext_binsearch fs/ext4/extents.c:841 [inline]
BUG: KASAN: use-after-free in ext4_find_extent+0xa36/0xa70 fs/ext4/extents.c:956
Read of size 4 at addr ffff8880126e4ff8 by task kworker/u8:8/25406

CPU: 0 UID: 0 PID: 25406 Comm: kworker/u8:8 Tainted: G    B               syzkaller #0 PREEMPT(full) 
Tainted: [B]=BAD_PAGE
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: writeback wb_workfn (flush-7:9)
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xcd/0x630 mm/kasan/report.c:482
 kasan_report+0xe0/0x110 mm/kasan/report.c:595
 ext4_ext_binsearch fs/ext4/extents.c:841 [inline]
 ext4_find_extent+0xa36/0xa70 fs/ext4/extents.c:956
 ext4_ext_map_blocks+0x290/0x5fe0 fs/ext4/extents.c:4208
 ext4_map_create_blocks fs/ext4/inode.c:609 [inline]
 ext4_map_blocks+0x570/0x1400 fs/ext4/inode.c:811
 mpage_map_one_extent fs/ext4/inode.c:2374 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2468 [inline]
 ext4_do_writepages+0x1ffa/0x3cf0 fs/ext4/inode.c:2931
 ext4_writepages+0x37a/0x7d0 fs/ext4/inode.c:3025
 do_writepages+0x27a/0x600 mm/page-writeback.c:2634
 __writeback_single_inode+0x160/0xfb0 fs/fs-writeback.c:1680
 writeback_sb_inodes+0x60d/0xfa0 fs/fs-writeback.c:1976
 wb_writeback+0x419/0xb70 fs/fs-writeback.c:2156
 wb_do_writeback fs/fs-writeback.c:2303 [inline]
 wb_workfn+0x14d/0xbe0 fs/fs-writeback.c:2343
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3236
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x3e5 pfn:0x126e4
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f0(buddy)
raw: 00fff00000000000 ffffea0001d8ce08 ffffea00012f0088 0000000000000000
raw: 00000000000003e5 0000000000000000 00000000f0000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 303, tgid 302 (syz.7.8407), ts 2513523256396, free_ts 2516257273897
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1851
 prep_new_page mm/page_alloc.c:1859 [inline]
 get_page_from_freelist+0x132b/0x38e0 mm/page_alloc.c:3858
 __alloc_frozen_pages_noprof+0x261/0x23f0 mm/page_alloc.c:5148
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2416
 folio_alloc_mpol_noprof+0x36/0x2f0 mm/mempolicy.c:2435
 shmem_alloc_folio+0x135/0x160 mm/shmem.c:1908
 shmem_alloc_and_add_folio+0x499/0xc20 mm/shmem.c:1947
 shmem_get_folio_gfp+0x67f/0x1600 mm/shmem.c:2597
 shmem_fault+0x1fe/0xa30 mm/shmem.c:2798
 __do_fault+0x10d/0x490 mm/memory.c:5152
 do_read_fault mm/memory.c:5573 [inline]
 do_fault mm/memory.c:5707 [inline]
 do_pte_missing+0xf50/0x3ba0 mm/memory.c:4234
 handle_pte_fault mm/memory.c:6052 [inline]
 __handle_mm_fault+0x152a/0x2a50 mm/memory.c:6195
 handle_mm_fault+0x589/0xd10 mm/memory.c:6364
 faultin_page mm/gup.c:1144 [inline]
 __get_user_pages+0x551/0x34a0 mm/gup.c:1446
 populate_vma_page_range+0x267/0x3f0 mm/gup.c:1880
 __mm_populate+0x1d8/0x380 mm/gup.c:1983
page last free pid 303 tgid 302 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1395 [inline]
 free_unref_folios+0xa61/0x16b0 mm/page_alloc.c:2952
 folios_put_refs+0x56f/0x740 mm/swap.c:997
 folio_batch_release include/linux/pagevec.h:101 [inline]
 shmem_undo_range+0x58f/0x1150 mm/shmem.c:1157
 shmem_truncate_range mm/shmem.c:1269 [inline]
 shmem_evict_inode+0x3a1/0xbe0 mm/shmem.c:1397
 evict+0x3e6/0x920 fs/inode.c:810
 iput_final fs/inode.c:1897 [inline]
 iput fs/inode.c:1923 [inline]
 iput+0x521/0x880 fs/inode.c:1909
 dentry_unlink_inode+0x29c/0x480 fs/dcache.c:466
 __dentry_kill+0x1d0/0x600 fs/dcache.c:669
 dput.part.0+0x4b1/0x9b0 fs/dcache.c:911
 dput+0x1f/0x30 fs/dcache.c:901
 __fput+0x51c/0xb70 fs/file_table.c:476
 task_work_run+0x150/0x240 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x86f/0x2bf0 kernel/exit.c:961
 do_group_exit+0xd3/0x2a0 kernel/exit.c:1102
 get_signal+0x2673/0x26d0 kernel/signal.c:3034
 arch_do_signal_or_restart+0x8f/0x7d0 arch/x86/kernel/signal.c:337

Memory state around the buggy address:
 ffff8880126e4e80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880126e4f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8880126e4f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                                ^
 ffff8880126e5000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8880126e5080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================
==================================================================
BUG: KASAN: use-after-free in ext4_ext_pblock fs/ext4/ext4_extents.h:224 [inline]
BUG: KASAN: use-after-free in ext4_find_extent+0xa57/0xa70 fs/ext4/extents.c:959
Read of size 2 at addr ffff8880126e4ffe by task kworker/u8:8/25406

CPU: 1 UID: 0 PID: 25406 Comm: kworker/u8:8 Tainted: G    B               syzkaller #0 PREEMPT(full) 
Tainted: [B]=BAD_PAGE
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: writeback wb_workfn (flush-7:9)
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xcd/0x630 mm/kasan/report.c:482
 kasan_report+0xe0/0x110 mm/kasan/report.c:595
 ext4_ext_pblock fs/ext4/ext4_extents.h:224 [inline]
 ext4_find_extent+0xa57/0xa70 fs/ext4/extents.c:959
 ext4_ext_map_blocks+0x290/0x5fe0 fs/ext4/extents.c:4208
 ext4_map_create_blocks fs/ext4/inode.c:609 [inline]
 ext4_map_blocks+0x570/0x1400 fs/ext4/inode.c:811
 mpage_map_one_extent fs/ext4/inode.c:2374 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2468 [inline]
 ext4_do_writepages+0x1ffa/0x3cf0 fs/ext4/inode.c:2931
 ext4_writepages+0x37a/0x7d0 fs/ext4/inode.c:3025
 do_writepages+0x27a/0x600 mm/page-writeback.c:2634
 __writeback_single_inode+0x160/0xfb0 fs/fs-writeback.c:1680
 writeback_sb_inodes+0x60d/0xfa0 fs/fs-writeback.c:1976
 wb_writeback+0x419/0xb70 fs/fs-writeback.c:2156
 wb_do_writeback fs/fs-writeback.c:2303 [inline]
 wb_workfn+0x14d/0xbe0 fs/fs-writeback.c:2343
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3236
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x3e5 pfn:0x126e4
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f0(buddy)
raw: 00fff00000000000 ffffea0001d8ce08 ffffea00012f0088 0000000000000000
raw: 00000000000003e5 0000000000000000 00000000f0000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 303, tgid 302 (syz.7.8407), ts 2513523256396, free_ts 2516257273897
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1851
 prep_new_page mm/page_alloc.c:1859 [inline]
 get_page_from_freelist+0x132b/0x38e0 mm/page_alloc.c:3858
 __alloc_frozen_pages_noprof+0x261/0x23f0 mm/page_alloc.c:5148
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2416
 folio_alloc_mpol_noprof+0x36/0x2f0 mm/mempolicy.c:2435
 shmem_alloc_folio+0x135/0x160 mm/shmem.c:1908
 shmem_alloc_and_add_folio+0x499/0xc20 mm/shmem.c:1947
 shmem_get_folio_gfp+0x67f/0x1600 mm/shmem.c:2597
 shmem_fault+0x1fe/0xa30 mm/shmem.c:2798
 __do_fault+0x10d/0x490 mm/memory.c:5152
 do_read_fault mm/memory.c:5573 [inline]
 do_fault mm/memory.c:5707 [inline]
 do_pte_missing+0xf50/0x3ba0 mm/memory.c:4234
 handle_pte_fault mm/memory.c:6052 [inline]
 __handle_mm_fault+0x152a/0x2a50 mm/memory.c:6195
 handle_mm_fault+0x589/0xd10 mm/memory.c:6364
 faultin_page mm/gup.c:1144 [inline]
 __get_user_pages+0x551/0x34a0 mm/gup.c:1446
 populate_vma_page_range+0x267/0x3f0 mm/gup.c:1880
 __mm_populate+0x1d8/0x380 mm/gup.c:1983
page last free pid 303 tgid 302 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1395 [inline]
 free_unref_folios+0xa61/0x16b0 mm/page_alloc.c:2952
 folios_put_refs+0x56f/0x740 mm/swap.c:997
 folio_batch_release include/linux/pagevec.h:101 [inline]
 shmem_undo_range+0x58f/0x1150 mm/shmem.c:1157
 shmem_truncate_range mm/shmem.c:1269 [inline]
 shmem_evict_inode+0x3a1/0xbe0 mm/shmem.c:1397
 evict+0x3e6/0x920 fs/inode.c:810
 iput_final fs/inode.c:1897 [inline]
 iput fs/inode.c:1923 [inline]
 iput+0x521/0x880 fs/inode.c:1909
 dentry_unlink_inode+0x29c/0x480 fs/dcache.c:466
 __dentry_kill+0x1d0/0x600 fs/dcache.c:669
 dput.part.0+0x4b1/0x9b0 fs/dcache.c:911
 dput+0x1f/0x30 fs/dcache.c:901
 __fput+0x51c/0xb70 fs/file_table.c:476
 task_work_run+0x150/0x240 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x86f/0x2bf0 kernel/exit.c:961
 do_group_exit+0xd3/0x2a0 kernel/exit.c:1102
 get_signal+0x2673/0x26d0 kernel/signal.c:3034
 arch_do_signal_or_restart+0x8f/0x7d0 arch/x86/kernel/signal.c:337

Memory state around the buggy address:
 ffff8880126e4e80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880126e4f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8880126e4f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                                ^
 ffff8880126e5000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8880126e5080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================
==================================================================
BUG: KASAN: use-after-free in ext4_ext_map_blocks+0x296e/0x5fe0 fs/ext4/extents.c:4232
Read of size 4 at addr ffff8880126e4ff8 by task kworker/u8:8/25406

CPU: 1 UID: 0 PID: 25406 Comm: kworker/u8:8 Tainted: G    B               syzkaller #0 PREEMPT(full) 
Tainted: [B]=BAD_PAGE
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: writeback wb_workfn (flush-7:9)
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xcd/0x630 mm/kasan/report.c:482
 kasan_report+0xe0/0x110 mm/kasan/report.c:595
 ext4_ext_map_blocks+0x296e/0x5fe0 fs/ext4/extents.c:4232
 ext4_map_create_blocks fs/ext4/inode.c:609 [inline]
 ext4_map_blocks+0x570/0x1400 fs/ext4/inode.c:811
 mpage_map_one_extent fs/ext4/inode.c:2374 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2468 [inline]
 ext4_do_writepages+0x1ffa/0x3cf0 fs/ext4/inode.c:2931
 ext4_writepages+0x37a/0x7d0 fs/ext4/inode.c:3025
 do_writepages+0x27a/0x600 mm/page-writeback.c:2634
 __writeback_single_inode+0x160/0xfb0 fs/fs-writeback.c:1680
 writeback_sb_inodes+0x60d/0xfa0 fs/fs-writeback.c:1976
 wb_writeback+0x419/0xb70 fs/fs-writeback.c:2156
 wb_do_writeback fs/fs-writeback.c:2303 [inline]
 wb_workfn+0x14d/0xbe0 fs/fs-writeback.c:2343
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3236
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x3e5 pfn:0x126e4
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f0(buddy)
raw: 00fff00000000000 ffffea0001d8ce08 ffffea00012f0088 0000000000000000
raw: 00000000000003e5 0000000000000000 00000000f0000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 303, tgid 302 (syz.7.8407), ts 2513523256396, free_ts 2516257273897
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1851
 prep_new_page mm/page_alloc.c:1859 [inline]
 get_page_from_freelist+0x132b/0x38e0 mm/page_alloc.c:3858
 __alloc_frozen_pages_noprof+0x261/0x23f0 mm/page_alloc.c:5148
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2416
 folio_alloc_mpol_noprof+0x36/0x2f0 mm/mempolicy.c:2435
 shmem_alloc_folio+0x135/0x160 mm/shmem.c:1908
 shmem_alloc_and_add_folio+0x499/0xc20 mm/shmem.c:1947
 shmem_get_folio_gfp+0x67f/0x1600 mm/shmem.c:2597
 shmem_fault+0x1fe/0xa30 mm/shmem.c:2798
 __do_fault+0x10d/0x490 mm/memory.c:5152
 do_read_fault mm/memory.c:5573 [inline]
 do_fault mm/memory.c:5707 [inline]
 do_pte_missing+0xf50/0x3ba0 mm/memory.c:4234
 handle_pte_fault mm/memory.c:6052 [inline]
 __handle_mm_fault+0x152a/0x2a50 mm/memory.c:6195
 handle_mm_fault+0x589/0xd10 mm/memory.c:6364
 faultin_page mm/gup.c:1144 [inline]
 __get_user_pages+0x551/0x34a0 mm/gup.c:1446
 populate_vma_page_range+0x267/0x3f0 mm/gup.c:1880
 __mm_populate+0x1d8/0x380 mm/gup.c:1983
page last free pid 303 tgid 302 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1395 [inline]
 free_unref_folios+0xa61/0x16b0 mm/page_alloc.c:2952
 folios_put_refs+0x56f/0x740 mm/swap.c:997
 folio_batch_release include/linux/pagevec.h:101 [inline]
 shmem_undo_range+0x58f/0x1150 mm/shmem.c:1157
 shmem_truncate_range mm/shmem.c:1269 [inline]
 shmem_evict_inode+0x3a1/0xbe0 mm/shmem.c:1397
 evict+0x3e6/0x920 fs/inode.c:810
 iput_final fs/inode.c:1897 [inline]
 iput fs/inode.c:1923 [inline]
 iput+0x521/0x880 fs/inode.c:1909
 dentry_unlink_inode+0x29c/0x480 fs/dcache.c:466
 __dentry_kill+0x1d0/0x600 fs/dcache.c:669
 dput.part.0+0x4b1/0x9b0 fs/dcache.c:911
 dput+0x1f/0x30 fs/dcache.c:901
 __fput+0x51c/0xb70 fs/file_table.c:476
 task_work_run+0x150/0x240 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x86f/0x2bf0 kernel/exit.c:961
 do_group_exit+0xd3/0x2a0 kernel/exit.c:1102
 get_signal+0x2673/0x26d0 kernel/signal.c:3034
 arch_do_signal_or_restart+0x8f/0x7d0 arch/x86/kernel/signal.c:337

Memory state around the buggy address:
 ffff8880126e4e80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880126e4f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8880126e4f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                                ^
 ffff8880126e5000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8880126e5080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================
==================================================================
BUG: KASAN: use-after-free in ext4_ext_pblock fs/ext4/ext4_extents.h:224 [inline]
BUG: KASAN: use-after-free in ext4_ext_map_blocks+0x2957/0x5fe0 fs/ext4/extents.c:4233
Read of size 2 at addr ffff8880126e4ffe by task kworker/u8:8/25406

CPU: 1 UID: 0 PID: 25406 Comm: kworker/u8:8 Tainted: G    B               syzkaller #0 PREEMPT(full) 
Tainted: [B]=BAD_PAGE
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: writeback wb_workfn (flush-7:9)
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xcd/0x630 mm/kasan/report.c:482
 kasan_report+0xe0/0x110 mm/kasan/report.c:595
 ext4_ext_pblock fs/ext4/ext4_extents.h:224 [inline]
 ext4_ext_map_blocks+0x2957/0x5fe0 fs/ext4/extents.c:4233
 ext4_map_create_blocks fs/ext4/inode.c:609 [inline]
 ext4_map_blocks+0x570/0x1400 fs/ext4/inode.c:811
 mpage_map_one_extent fs/ext4/inode.c:2374 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2468 [inline]
 ext4_do_writepages+0x1ffa/0x3cf0 fs/ext4/inode.c:2931
 ext4_writepages+0x37a/0x7d0 fs/ext4/inode.c:3025
 do_writepages+0x27a/0x600 mm/page-writeback.c:2634
 __writeback_single_inode+0x160/0xfb0 fs/fs-writeback.c:1680
 writeback_sb_inodes+0x60d/0xfa0 fs/fs-writeback.c:1976
 wb_writeback+0x419/0xb70 fs/fs-writeback.c:2156
 wb_do_writeback fs/fs-writeback.c:2303 [inline]
 wb_workfn+0x14d/0xbe0 fs/fs-writeback.c:2343
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3236
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x3e5 pfn:0x126e4
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f0(buddy)
raw: 00fff00000000000 ffffea0001d8ce08 ffffea00012f0088 0000000000000000
raw: 00000000000003e5 0000000000000000 00000000f0000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 303, tgid 302 (syz.7.8407), ts 2513523256396, free_ts 2516257273897
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1851
 prep_new_page mm/page_alloc.c:1859 [inline]
 get_page_from_freelist+0x132b/0x38e0 mm/page_alloc.c:3858
 __alloc_frozen_pages_noprof+0x261/0x23f0 mm/page_alloc.c:5148
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2416
 folio_alloc_mpol_noprof+0x36/0x2f0 mm/mempolicy.c:2435
 shmem_alloc_folio+0x135/0x160 mm/shmem.c:1908
 shmem_alloc_and_add_folio+0x499/0xc20 mm/shmem.c:1947
 shmem_get_folio_gfp+0x67f/0x1600 mm/shmem.c:2597
 shmem_fault+0x1fe/0xa30 mm/shmem.c:2798
 __do_fault+0x10d/0x490 mm/memory.c:5152
 do_read_fault mm/memory.c:5573 [inline]
 do_fault mm/memory.c:5707 [inline]
 do_pte_missing+0xf50/0x3ba0 mm/memory.c:4234
 handle_pte_fault mm/memory.c:6052 [inline]
 __handle_mm_fault+0x152a/0x2a50 mm/memory.c:6195
 handle_mm_fault+0x589/0xd10 mm/memory.c:6364
 faultin_page mm/gup.c:1144 [inline]
 __get_user_pages+0x551/0x34a0 mm/gup.c:1446
 populate_vma_page_range+0x267/0x3f0 mm/gup.c:1880
 __mm_populate+0x1d8/0x380 mm/gup.c:1983
page last free pid 303 tgid 302 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1395 [inline]
 free_unref_folios+0xa61/0x16b0 mm/page_alloc.c:2952
 folios_put_refs+0x56f/0x740 mm/swap.c:997
 folio_batch_release include/linux/pagevec.h:101 [inline]
 shmem_undo_range+0x58f/0x1150 mm/shmem.c:1157
 shmem_truncate_range mm/shmem.c:1269 [inline]
 shmem_evict_inode+0x3a1/0xbe0 mm/shmem.c:1397
 evict+0x3e6/0x920 fs/inode.c:810
 iput_final fs/inode.c:1897 [inline]
 iput fs/inode.c:1923 [inline]
 iput+0x521/0x880 fs/inode.c:1909
 dentry_unlink_inode+0x29c/0x480 fs/dcache.c:466
 __dentry_kill+0x1d0/0x600 fs/dcache.c:669
 dput.part.0+0x4b1/0x9b0 fs/dcache.c:911
 dput+0x1f/0x30 fs/dcache.c:901
 __fput+0x51c/0xb70 fs/file_table.c:476
 task_work_run+0x150/0x240 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x86f/0x2bf0 kernel/exit.c:961
 do_group_exit+0xd3/0x2a0 kernel/exit.c:1102
 get_signal+0x2673/0x26d0 kernel/signal.c:3034
 arch_do_signal_or_restart+0x8f/0x7d0 arch/x86/kernel/signal.c:337

Memory state around the buggy address:
 ffff8880126e4e80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880126e4f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8880126e4f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                                ^
 ffff8880126e5000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8880126e5080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================
==================================================================
BUG: KASAN: use-after-free in ext4_ext_get_actual_len fs/ext4/ext4_extents.h:205 [inline]
BUG: KASAN: use-after-free in ext4_ext_map_blocks+0x297b/0x5fe0 fs/ext4/extents.c:4241
Read of size 2 at addr ffff8880126e4ffc by task kworker/u8:8/25406

CPU: 1 UID: 0 PID: 25406 Comm: kworker/u8:8 Tainted: G    B               syzkaller #0 PREEMPT(full) 
Tainted: [B]=BAD_PAGE
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: writeback wb_workfn (flush-7:9)
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xcd/0x630 mm/kasan/report.c:482
 kasan_report+0xe0/0x110 mm/kasan/report.c:595
 ext4_ext_get_actual_len fs/ext4/ext4_extents.h:205 [inline]
 ext4_ext_map_blocks+0x297b/0x5fe0 fs/ext4/extents.c:4241
 ext4_map_create_blocks fs/ext4/inode.c:609 [inline]
 ext4_map_blocks+0x570/0x1400 fs/ext4/inode.c:811
 mpage_map_one_extent fs/ext4/inode.c:2374 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2468 [inline]
 ext4_do_writepages+0x1ffa/0x3cf0 fs/ext4/inode.c:2931
 ext4_writepages+0x37a/0x7d0 fs/ext4/inode.c:3025
 do_writepages+0x27a/0x600 mm/page-writeback.c:2634
 __writeback_single_inode+0x160/0xfb0 fs/fs-writeback.c:1680
 writeback_sb_inodes+0x60d/0xfa0 fs/fs-writeback.c:1976
 wb_writeback+0x419/0xb70 fs/fs-writeback.c:2156
 wb_do_writeback fs/fs-writeback.c:2303 [inline]
 wb_workfn+0x14d/0xbe0 fs/fs-writeback.c:2343
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3236
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x3e5 pfn:0x126e4
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f0(buddy)
raw: 00fff00000000000 ffffea0001d8ce08 ffffea00012f0088 0000000000000000
raw: 00000000000003e5 0000000000000000 00000000f0000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 303, tgid 302 (syz.7.8407), ts 2513523256396, free_ts 2516257273897
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1851
 prep_new_page mm/page_alloc.c:1859 [inline]
 get_page_from_freelist+0x132b/0x38e0 mm/page_alloc.c:3858
 __alloc_frozen_pages_noprof+0x261/0x23f0 mm/page_alloc.c:5148
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2416
 folio_alloc_mpol_noprof+0x36/0x2f0 mm/mempolicy.c:2435
 shmem_alloc_folio+0x135/0x160 mm/shmem.c:1908
 shmem_alloc_and_add_folio+0x499/0xc20 mm/shmem.c:1947
 shmem_get_folio_gfp+0x67f/0x1600 mm/shmem.c:2597
 shmem_fault+0x1fe/0xa30 mm/shmem.c:2798
 __do_fault+0x10d/0x490 mm/memory.c:5152
 do_read_fault mm/memory.c:5573 [inline]
 do_fault mm/memory.c:5707 [inline]
 do_pte_missing+0xf50/0x3ba0 mm/memory.c:4234
 handle_pte_fault mm/memory.c:6052 [inline]
 __handle_mm_fault+0x152a/0x2a50 mm/memory.c:6195
 handle_mm_fault+0x589/0xd10 mm/memory.c:6364
 faultin_page mm/gup.c:1144 [inline]
 __get_user_pages+0x551/0x34a0 mm/gup.c:1446
 populate_vma_page_range+0x267/0x3f0 mm/gup.c:1880
 __mm_populate+0x1d8/0x380 mm/gup.c:1983
page last free pid 303 tgid 302 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1395 [inline]
 free_unref_folios+0xa61/0x16b0 mm/page_alloc.c:2952
 folios_put_refs+0x56f/0x740 mm/swap.c:997
 folio_batch_release include/linux/pagevec.h:101 [inline]
 shmem_undo_range+0x58f/0x1150 mm/shmem.c:1157
 shmem_truncate_range mm/shmem.c:1269 [inline]
 shmem_evict_inode+0x3a1/0xbe0 mm/shmem.c:1397
 evict+0x3e6/0x920 fs/inode.c:810
 iput_final fs/inode.c:1897 [inline]
 iput fs/inode.c:1923 [inline]
 iput+0x521/0x880 fs/inode.c:1909
 dentry_unlink_inode+0x29c/0x480 fs/dcache.c:466
 __dentry_kill+0x1d0/0x600 fs/dcache.c:669
 dput.part.0+0x4b1/0x9b0 fs/dcache.c:911
 dput+0x1f/0x30 fs/dcache.c:901
 __fput+0x51c/0xb70 fs/file_table.c:476
 task_work_run+0x150/0x240 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x86f/0x2bf0 kernel/exit.c:961
 do_group_exit+0xd3/0x2a0 kernel/exit.c:1102
 get_signal+0x2673/0x26d0 kernel/signal.c:3034
 arch_do_signal_or_restart+0x8f/0x7d0 arch/x86/kernel/signal.c:337

Memory state around the buggy address:
 ffff8880126e4e80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880126e4f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8880126e4f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                                ^
 ffff8880126e5000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8880126e5080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================
==================================================================
BUG: KASAN: use-after-free in ext4_ext_get_actual_len fs/ext4/ext4_extents.h:205 [inline]
BUG: KASAN: use-after-free in ext4_ext_search_left fs/ext4/extents.c:1490 [inline]
BUG: KASAN: use-after-free in ext4_ext_map_blocks+0x2985/0x5fe0 fs/ext4/extents.c:4316
Read of size 2 at addr ffff8880126e4ffc by task kworker/u8:8/25406

CPU: 1 UID: 0 PID: 25406 Comm: kworker/u8:8 Tainted: G    B               syzkaller #0 PREEMPT(full) 
Tainted: [B]=BAD_PAGE
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: writeback wb_workfn (flush-7:9)
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xcd/0x630 mm/kasan/report.c:482
 kasan_report+0xe0/0x110 mm/kasan/report.c:595
 ext4_ext_get_actual_len fs/ext4/ext4_extents.h:205 [inline]
 ext4_ext_search_left fs/ext4/extents.c:1490 [inline]
 ext4_ext_map_blocks+0x2985/0x5fe0 fs/ext4/extents.c:4316
 ext4_map_create_blocks fs/ext4/inode.c:609 [inline]
 ext4_map_blocks+0x570/0x1400 fs/ext4/inode.c:811
 mpage_map_one_extent fs/ext4/inode.c:2374 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2468 [inline]
 ext4_do_writepages+0x1ffa/0x3cf0 fs/ext4/inode.c:2931
 ext4_writepages+0x37a/0x7d0 fs/ext4/inode.c:3025
 do_writepages+0x27a/0x600 mm/page-writeback.c:2634
 __writeback_single_inode+0x160/0xfb0 fs/fs-writeback.c:1680
 writeback_sb_inodes+0x60d/0xfa0 fs/fs-writeback.c:1976
 wb_writeback+0x419/0xb70 fs/fs-writeback.c:2156
 wb_do_writeback fs/fs-writeback.c:2303 [inline]
 wb_workfn+0x14d/0xbe0 fs/fs-writeback.c:2343
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3236
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x3e5 pfn:0x126e4
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f0(buddy)
raw: 00fff00000000000 ffffea0001d8ce08 ffffea00012f0088 0000000000000000
raw: 00000000000003e5 0000000000000000 00000000f0000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 303, tgid 302 (syz.7.8407), ts 2513523256396, free_ts 2516257273897
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1851
 prep_new_page mm/page_alloc.c:1859 [inline]
 get_page_from_freelist+0x132b/0x38e0 mm/page_alloc.c:3858
 __alloc_frozen_pages_noprof+0x261/0x23f0 mm/page_alloc.c:5148
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2416
 folio_alloc_mpol_noprof+0x36/0x2f0 mm/mempolicy.c:2435
 shmem_alloc_folio+0x135/0x160 mm/shmem.c:1908
 shmem_alloc_and_add_folio+0x499/0xc20 mm/shmem.c:1947
 shmem_get_folio_gfp+0x67f/0x1600 mm/shmem.c:2597
 shmem_fault+0x1fe/0xa30 mm/shmem.c:2798
 __do_fault+0x10d/0x490 mm/memory.c:5152
 do_read_fault mm/memory.c:5573 [inline]
 do_fault mm/memory.c:5707 [inline]
 do_pte_missing+0xf50/0x3ba0 mm/memory.c:4234
 handle_pte_fault mm/memory.c:6052 [inline]
 __handle_mm_fault+0x152a/0x2a50 mm/memory.c:6195
 handle_mm_fault+0x589/0xd10 mm/memory.c:6364
 faultin_page mm/gup.c:1144 [inline]
 __get_user_pages+0x551/0x34a0 mm/gup.c:1446
 populate_vma_page_range+0x267/0x3f0 mm/gup.c:1880
 __mm_populate+0x1d8/0x380 mm/gup.c:1983
page last free pid 303 tgid 302 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1395 [inline]
 free_unref_folios+0xa61/0x16b0 mm/page_alloc.c:2952
 folios_put_refs+0x56f/0x740 mm/swap.c:997
 folio_batch_release include/linux/pagevec.h:101 [inline]
 shmem_undo_range+0x58f/0x1150 mm/shmem.c:1157
 shmem_truncate_range mm/shmem.c:1269 [inline]
 shmem_evict_inode+0x3a1/0xbe0 mm/shmem.c:1397
 evict+0x3e6/0x920 fs/inode.c:810
 iput_final fs/inode.c:1897 [inline]
 iput fs/inode.c:1923 [inline]
 iput+0x521/0x880 fs/inode.c:1909
 dentry_unlink_inode+0x29c/0x480 fs/dcache.c:466
 __dentry_kill+0x1d0/0x600 fs/dcache.c:669
 dput.part.0+0x4b1/0x9b0 fs/dcache.c:911
 dput+0x1f/0x30 fs/dcache.c:901
 __fput+0x51c/0xb70 fs/file_table.c:476
 task_work_run+0x150/0x240 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x86f/0x2bf0 kernel/exit.c:961
 do_group_exit+0xd3/0x2a0 kernel/exit.c:1102
 get_signal+0x2673/0x26d0 kernel/signal.c:3034
 arch_do_signal_or_restart+0x8f/0x7d0 arch/x86/kernel/signal.c:337

Memory state around the buggy address:
 ffff8880126e4e80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880126e4f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8880126e4f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                                ^
 ffff8880126e5000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8880126e5080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================
==================================================================
BUG: KASAN: use-after-free in ext4_ext_search_left fs/ext4/extents.c:1491 [inline]
BUG: KASAN: use-after-free in ext4_ext_map_blocks+0x5119/0x5fe0 fs/ext4/extents.c:4316
Read of size 4 at addr ffff8880126e4ff8 by task kworker/u8:8/25406

CPU: 0 UID: 0 PID: 25406 Comm: kworker/u8:8 Tainted: G    B               syzkaller #0 PREEMPT(full) 
Tainted: [B]=BAD_PAGE
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: writeback wb_workfn (flush-7:9)
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xcd/0x630 mm/kasan/report.c:482
 kasan_report+0xe0/0x110 mm/kasan/report.c:595
 ext4_ext_search_left fs/ext4/extents.c:1491 [inline]
 ext4_ext_map_blocks+0x5119/0x5fe0 fs/ext4/extents.c:4316
 ext4_map_create_blocks fs/ext4/inode.c:609 [inline]
 ext4_map_blocks+0x570/0x1400 fs/ext4/inode.c:811
 mpage_map_one_extent fs/ext4/inode.c:2374 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2468 [inline]
 ext4_do_writepages+0x1ffa/0x3cf0 fs/ext4/inode.c:2931
 ext4_writepages+0x37a/0x7d0 fs/ext4/inode.c:3025
 do_writepages+0x27a/0x600 mm/page-writeback.c:2634
 __writeback_single_inode+0x160/0xfb0 fs/fs-writeback.c:1680
 writeback_sb_inodes+0x60d/0xfa0 fs/fs-writeback.c:1976
 wb_writeback+0x419/0xb70 fs/fs-writeback.c:2156
 wb_do_writeback fs/fs-writeback.c:2303 [inline]
 wb_workfn+0x14d/0xbe0 fs/fs-writeback.c:2343
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3236
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x3e5 pfn:0x126e4
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f0(buddy)
raw: 00fff00000000000 ffffea0001d8ce08 ffffea00012f0088 0000000000000000
raw: 00000000000003e5 0000000000000000 00000000f0000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 303, tgid 302 (syz.7.8407), ts 2513523256396, free_ts 2516257273897
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1851
 prep_new_page mm/page_alloc.c:1859 [inline]
 get_page_from_freelist+0x132b/0x38e0 mm/page_alloc.c:3858
 __alloc_frozen_pages_noprof+0x261/0x23f0 mm/page_alloc.c:5148
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2416
 folio_alloc_mpol_noprof+0x36/0x2f0 mm/mempolicy.c:2435
 shmem_alloc_folio+0x135/0x160 mm/shmem.c:1908
 shmem_alloc_and_add_folio+0x499/0xc20 mm/shmem.c:1947
 shmem_get_folio_gfp+0x67f/0x1600 mm/shmem.c:2597
 shmem_fault+0x1fe/0xa30 mm/shmem.c:2798
 __do_fault+0x10d/0x490 mm/memory.c:5152
 do_read_fault mm/memory.c:5573 [inline]
 do_fault mm/memory.c:5707 [inline]
 do_pte_missing+0xf50/0x3ba0 mm/memory.c:4234
 handle_pte_fault mm/memory.c:6052 [inline]
 __handle_mm_fault+0x152a/0x2a50 mm/memory.c:6195
 handle_mm_fault+0x589/0xd10 mm/memory.c:6364
 faultin_page mm/gup.c:1144 [inline]
 __get_user_pages+0x551/0x34a0 mm/gup.c:1446
 populate_vma_page_range+0x267/0x3f0 mm/gup.c:1880
 __mm_populate+0x1d8/0x380 mm/gup.c:1983
page last free pid 303 tgid 302 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1395 [inline]
 free_unref_folios+0xa61/0x16b0 mm/page_alloc.c:2952
 folios_put_refs+0x56f/0x740 mm/swap.c:997
 folio_batch_release include/linux/pagevec.h:101 [inline]
 shmem_undo_range+0x58f/0x1150 mm/shmem.c:1157
 shmem_truncate_range mm/shmem.c:1269 [inline]
 shmem_evict_inode+0x3a1/0xbe0 mm/shmem.c:1397
 evict+0x3e6/0x920 fs/inode.c:810
 iput_final fs/inode.c:1897 [inline]
 iput fs/inode.c:1923 [inline]
 iput+0x521/0x880 fs/inode.c:1909
 dentry_unlink_inode+0x29c/0x480 fs/dcache.c:466
 __dentry_kill+0x1d0/0x600 fs/dcache.c:669
 dput.part.0+0x4b1/0x9b0 fs/dcache.c:911
 dput+0x1f/0x30 fs/dcache.c:901
 __fput+0x51c/0xb70 fs/file_table.c:476
 task_work_run+0x150/0x240 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x86f/0x2bf0 kernel/exit.c:961
 do_group_exit+0xd3/0x2a0 kernel/exit.c:1102
 get_signal+0x2673/0x26d0 kernel/signal.c:3034
 arch_do_signal_or_restart+0x8f/0x7d0 arch/x86/kernel/signal.c:337

Memory state around the buggy address:
 ffff8880126e4e80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880126e4f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8880126e4f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                                ^
 ffff8880126e5000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8880126e5080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================
==================================================================
BUG: KASAN: use-after-free in ext4_ext_pblock fs/ext4/ext4_extents.h:224 [inline]
BUG: KASAN: use-after-free in ext4_ext_search_left fs/ext4/extents.c:1520 [inline]
BUG: KASAN: use-after-free in ext4_ext_map_blocks+0x5151/0x5fe0 fs/ext4/extents.c:4316
Read of size 2 at addr ffff8880126e4ffe by task kworker/u8:8/25406

CPU: 0 UID: 0 PID: 25406 Comm: kworker/u8:8 Tainted: G    B               syzkaller #0 PREEMPT(full) 
Tainted: [B]=BAD_PAGE
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: writeback wb_workfn (flush-7:9)
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xcd/0x630 mm/kasan/report.c:482
 kasan_report+0xe0/0x110 mm/kasan/report.c:595
 ext4_ext_pblock fs/ext4/ext4_extents.h:224 [inline]
 ext4_ext_search_left fs/ext4/extents.c:1520 [inline]
 ext4_ext_map_blocks+0x5151/0x5fe0 fs/ext4/extents.c:4316
 ext4_map_create_blocks fs/ext4/inode.c:609 [inline]
 ext4_map_blocks+0x570/0x1400 fs/ext4/inode.c:811
 mpage_map_one_extent fs/ext4/inode.c:2374 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2468 [inline]
 ext4_do_writepages+0x1ffa/0x3cf0 fs/ext4/inode.c:2931
 ext4_writepages+0x37a/0x7d0 fs/ext4/inode.c:3025
 do_writepages+0x27a/0x600 mm/page-writeback.c:2634
 __writeback_single_inode+0x160/0xfb0 fs/fs-writeback.c:1680
 writeback_sb_inodes+0x60d/0xfa0 fs/fs-writeback.c:1976
 wb_writeback+0x419/0xb70 fs/fs-writeback.c:2156
 wb_do_writeback fs/fs-writeback.c:2303 [inline]
 wb_workfn+0x14d/0xbe0 fs/fs-writeback.c:2343
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3236
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x3e5 pfn:0x126e4
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f0(buddy)
raw: 00fff00000000000 ffffea0001d8ce08 ffffea00012f0088 0000000000000000
raw: 00000000000003e5 0000000000000000 00000000f0000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 303, tgid 302 (syz.7.8407), ts 2513523256396, free_ts 2516257273897
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1851
 prep_new_page mm/page_alloc.c:1859 [inline]
 get_page_from_freelist+0x132b/0x38e0 mm/page_alloc.c:3858
 __alloc_frozen_pages_noprof+0x261/0x23f0 mm/page_alloc.c:5148
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2416
 folio_alloc_mpol_noprof+0x36/0x2f0 mm/mempolicy.c:2435
 shmem_alloc_folio+0x135/0x160 mm/shmem.c:1908
 shmem_alloc_and_add_folio+0x499/0xc20 mm/shmem.c:1947
 shmem_get_folio_gfp+0x67f/0x1600 mm/shmem.c:2597
 shmem_fault+0x1fe/0xa30 mm/shmem.c:2798
 __do_fault+0x10d/0x490 mm/memory.c:5152
 do_read_fault mm/memory.c:5573 [inline]
 do_fault mm/memory.c:5707 [inline]
 do_pte_missing+0xf50/0x3ba0 mm/memory.c:4234
 handle_pte_fault mm/memory.c:6052 [inline]
 __handle_mm_fault+0x152a/0x2a50 mm/memory.c:6195
 handle_mm_fault+0x589/0xd10 mm/memory.c:6364
 faultin_page mm/gup.c:1144 [inline]
 __get_user_pages+0x551/0x34a0 mm/gup.c:1446
 populate_vma_page_range+0x267/0x3f0 mm/gup.c:1880
 __mm_populate+0x1d8/0x380 mm/gup.c:1983
page last free pid 303 tgid 302 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1395 [inline]
 free_unref_folios+0xa61/0x16b0 mm/page_alloc.c:2952
 folios_put_refs+0x56f/0x740 mm/swap.c:997
 folio_batch_release include/linux/pagevec.h:101 [inline]
 shmem_undo_range+0x58f/0x1150 mm/shmem.c:1157
 shmem_truncate_range mm/shmem.c:1269 [inline]
 shmem_evict_inode+0x3a1/0xbe0 mm/shmem.c:1397
 evict+0x3e6/0x920 fs/inode.c:810
 iput_final fs/inode.c:1897 [inline]
 iput fs/inode.c:1923 [inline]
 iput+0x521/0x880 fs/inode.c:1909
 dentry_unlink_inode+0x29c/0x480 fs/dcache.c:466
 __dentry_kill+0x1d0/0x600 fs/dcache.c:669
 dput.part.0+0x4b1/0x9b0 fs/dcache.c:911
 dput+0x1f/0x30 fs/dcache.c:901
 __fput+0x51c/0xb70 fs/file_table.c:476
 task_work_run+0x150/0x240 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x86f/0x2bf0 kernel/exit.c:961
 do_group_exit+0xd3/0x2a0 kernel/exit.c:1102
 get_signal+0x2673/0x26d0 kernel/signal.c:3034
 arch_do_signal_or_restart+0x8f/0x7d0 arch/x86/kernel/signal.c:337

Memory state around the buggy address:
 ffff8880126e4e80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880126e4f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8880126e4f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                                ^
 ffff8880126e5000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8880126e5080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================
==================================================================
BUG: KASAN: use-after-free in ext4_ext_get_actual_len fs/ext4/ext4_extents.h:205 [inline]
BUG: KASAN: use-after-free in ext4_ext_search_right+0x8eb/0xba0 fs/ext4/extents.c:1558
Read of size 2 at addr ffff8880126e4ffc by task kworker/u8:8/25406

CPU: 1 UID: 0 PID: 25406 Comm: kworker/u8:8 Tainted: G    B               syzkaller #0 PREEMPT(full) 
Tainted: [B]=BAD_PAGE
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: writeback wb_workfn (flush-7:9)
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xcd/0x630 mm/kasan/report.c:482
 kasan_report+0xe0/0x110 mm/kasan/report.c:595
 ext4_ext_get_actual_len fs/ext4/ext4_extents.h:205 [inline]
 ext4_ext_search_right+0x8eb/0xba0 fs/ext4/extents.c:1558
 ext4_ext_map_blocks+0x134b/0x5fe0 fs/ext4/extents.c:4320
 ext4_map_create_blocks fs/ext4/inode.c:609 [inline]
 ext4_map_blocks+0x570/0x1400 fs/ext4/inode.c:811
 mpage_map_one_extent fs/ext4/inode.c:2374 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2468 [inline]
 ext4_do_writepages+0x1ffa/0x3cf0 fs/ext4/inode.c:2931
 ext4_writepages+0x37a/0x7d0 fs/ext4/inode.c:3025