==================================================================
BUG: KASAN: use-after-free in ext4_ext_binsearch fs/ext4/extents.c:826 [inline]
BUG: KASAN: use-after-free in ext4_find_extent+0xbeb/0xe20 fs/ext4/extents.c:945
Read of size 4 at addr ffff88812165c078 by task kworker/u4:1/9

CPU: 1 PID: 9 Comm: kworker/u4:1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: writeback wb_workfn (flush-7:0)

Call Trace:
 __dump_stack+0x21/0x24 lib/dump_stack.c:77
 dump_stack_lvl+0x169/0x1d8 lib/dump_stack.c:118
 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:435 [inline]
 kasan_report+0xe2/0x130 mm/kasan/report.c:452
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:308
 ext4_ext_binsearch fs/ext4/extents.c:826 [inline]
 ext4_find_extent+0xbeb/0xe20 fs/ext4/extents.c:945
 ext4_ext_map_blocks+0x1dc/0x5d80 fs/ext4/extents.c:4160
 ext4_map_blocks+0x978/0x1bc0 fs/ext4/inode.c:674
 mpage_map_one_extent fs/ext4/inode.c:2452 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2505 [inline]
 ext4_writepages+0x11d5/0x2e00 fs/ext4/inode.c:2873
 do_writepages+0x12a/0x270 mm/page-writeback.c:2380
 __writeback_single_inode+0xd5/0xa20 fs/fs-writeback.c:1470
 writeback_sb_inodes+0x860/0x1400 fs/fs-writeback.c:1733
 wb_writeback+0x3e3/0xb90 fs/fs-writeback.c:1908
 wb_do_writeback fs/fs-writeback.c:2053 [inline]
 wb_workfn+0x38f/0xe20 fs/fs-writeback.c:2094
 process_one_work+0x6e1/0xba0 kernel/workqueue.c:2301
 worker_thread+0xa6a/0x13b0 kernel/workqueue.c:2447
 kthread+0x346/0x3d0 kernel/kthread.c:313
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298

The buggy address belongs to the page:
page:ffffea0004859700 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x12165c
flags: 0x4000000000000000()
raw: 4000000000000000 ffffea00048596c8 ffffea00048541c8 0000000000000000
raw: 0000000000000001 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 0x8100dca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO|0x8000000), pid 327, ts 38523346012, free_ts 38524152864
 set_page_owner include/linux/page_owner.h:35 [inline]
 post_alloc_hook mm/page_alloc.c:2456 [inline]
 prep_new_page+0x179/0x180 mm/page_alloc.c:2462
 get_page_from_freelist+0x2235/0x23d0 mm/page_alloc.c:4254
 __alloc_pages_nodemask+0x268/0x5f0 mm/page_alloc.c:5370
 __alloc_pages include/linux/gfp.h:544 [inline]
 __alloc_pages_node include/linux/gfp.h:557 [inline]
 alloc_pages_node include/linux/gfp.h:571 [inline]
 alloc_pages include/linux/gfp.h:590 [inline]
 do_anonymous_page mm/memory.c:3963 [inline]
 handle_pte_fault+0x1719/0x3750 mm/memory.c:4786
 __handle_mm_fault mm/memory.c:4944 [inline]
 handle_mm_fault+0xf3f/0x16a0 mm/memory.c:5358
 do_user_addr_fault+0x5a2/0xc80 arch/x86/mm/fault.c:1362
 handle_page_fault arch/x86/mm/fault.c:1428 [inline]
 exc_page_fault+0x5a/0xc0 arch/x86/mm/fault.c:1484
 asm_exc_page_fault+0x1e/0x30 arch/x86/include/asm/idtentry.h:571
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:28 [inline]
 free_pages_prepare mm/page_alloc.c:1349 [inline]
 free_pcp_prepare mm/page_alloc.c:1421 [inline]
 free_unref_page_prepare+0x2b7/0x2d0 mm/page_alloc.c:3336
 free_unref_page_list+0x12e/0x9b0 mm/page_alloc.c:3443
 release_pages+0xe38/0xe80 mm/swap.c:1103
 free_pages_and_swap_cache+0x86/0xa0 mm/swap_state.c:356
 tlb_batch_pages_flush mm/mmu_gather.c:49 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:240 [inline]
 tlb_flush_mmu mm/mmu_gather.c:247 [inline]
 tlb_finish_mmu+0x175/0x300 mm/mmu_gather.c:326
 unmap_region+0x32c/0x380 mm/mmap.c:2811
 __do_munmap+0x63c/0x850 mm/mmap.c:3041
 __vm_munmap mm/mmap.c:3094 [inline]
 __do_sys_munmap mm/mmap.c:3120 [inline]
 __se_sys_munmap+0x127/0x1b0 mm/mmap.c:3116
 __x64_sys_munmap+0x5b/0x70 mm/mmap.c:3116
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

Memory state around the buggy address:
 ffff88812165bf00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88812165bf80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88812165c000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                                ^
 ffff88812165c080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88812165c100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
EXT4-fs (loop0): Delayed block allocation failed for inode 19 at logical offset 0 with max blocks 16 with error 28
EXT4-fs (loop0): This should not happen!! Data will be lost

EXT4-fs (loop0): Total free blocks count 0
EXT4-fs (loop0): Free/Dirty block details
EXT4-fs (loop0): free_blocks=0
EXT4-fs (loop0): dirty_blocks=0
EXT4-fs (loop0): Block reservation details
EXT4-fs (loop0): i_reserved_data_blocks=0
EXT4-fs error (device loop0): __ext4_get_inode_loc:4444: comm kworker/u4:1: Invalid inode table block 0 in block_group 0
EXT4-fs error (device loop0): __ext4_get_inode_loc:4444: comm kworker/u4:1: Invalid inode table block 0 in block_group 0
EXT4-fs (loop0): Delayed block allocation failed for inode 19 at logical offset 0 with max blocks 16 with error 28
EXT4-fs (loop0): This should not happen!! Data will be lost

EXT4-fs (loop0): Total free blocks count 0
EXT4-fs (loop0): Free/Dirty block details
EXT4-fs (loop0): free_blocks=0
EXT4-fs (loop0): dirty_blocks=0
EXT4-fs (loop0): Block reservation details
EXT4-fs (loop0): i_reserved_data_blocks=0
EXT4-fs error (device loop0): __ext4_get_inode_loc:4444: comm kworker/u4:1: Invalid inode table block 0 in block_group 0
EXT4-fs error (device loop0): __ext4_get_inode_loc:4444: comm kworker/u4:1: Invalid inode table block 0 in block_group 0
EXT4-fs (loop0): Delayed block allocation failed for inode 19 at logical offset 0 with max blocks 16 with error 28
EXT4-fs (loop0): This should not happen!! Data will be lost

EXT4-fs (loop0): Total free blocks count 0
EXT4-fs (loop0): Free/Dirty block details
EXT4-fs (loop0): free_blocks=0
EXT4-fs (loop0): dirty_blocks=0
EXT4-fs (loop0): Block reservation details
EXT4-fs (loop0): i_reserved_data_blocks=0
EXT4-fs error (device loop0): __ext4_get_inode_loc:4444: comm kworker/u4:1: Invalid inode table block 0 in block_group 0
EXT4-fs error (device loop0): __ext4_get_inode_loc:4444: comm kworker/u4:1: Invalid inode table block 0 in block_group 0
EXT4-fs (loop0): Delayed block allocation failed for inode 19 at logical offset 0 with max blocks 16 with error 28
EXT4-fs (loop0): This should not happen!! Data will be lost

EXT4-fs (loop0): Total free blocks count 0
EXT4-fs (loop0): Free/Dirty block details
EXT4-fs (loop0): free_blocks=0
EXT4-fs (loop0): dirty_blocks=0
EXT4-fs (loop0): Block reservation details
EXT4-fs (loop0): i_reserved_data_blocks=0
EXT4-fs error (device loop0): __ext4_get_inode_loc:4444: comm kworker/u4:1: Invalid inode table block 0 in block_group 0
EXT4-fs error (device loop0): __ext4_get_inode_loc:4444: comm kworker/u4:1: Invalid inode table block 0 in block_group 0
EXT4-fs (loop0): Delayed block allocation failed for inode 19 at logical offset 0 with max blocks 16 with error 28
EXT4-fs (loop0): This should not happen!! Data will be lost

EXT4-fs (loop0): Total free blocks count 0
EXT4-fs (loop0): Free/Dirty block details
EXT4-fs (loop0): free_blocks=0
EXT4-fs (loop0): dirty_blocks=0
EXT4-fs (loop0): Block reservation details
EXT4-fs (loop0): i_reserved_data_blocks=0
EXT4-fs error (device loop0): __ext4_get_inode_loc:4444: comm kworker/u4:1: Invalid inode table block 0 in block_group 0
EXT4-fs error (device loop0): __ext4_get_inode_loc:4444: comm kworker/u4:1: Invalid inode table block 0 in block_group 0
EXT4-fs (loop0): Delayed block allocation failed for inode 19 at logical offset 0 with max blocks 16 with error 28
EXT4-fs (loop0): This should not happen!! Data will be lost

EXT4-fs (loop0): Total free blocks count 0
EXT4-fs (loop0): Free/Dirty block details
EXT4-fs (loop0): free_blocks=0
EXT4-fs (loop0): dirty_blocks=0
EXT4-fs (loop0): Block reservation details
EXT4-fs (loop0): i_reserved_data_blocks=0
EXT4-fs error (device loop0): __ext4_get_inode_loc:4444: comm kworker/u4:1: Invalid inode table block 0 in block_group 0
EXT4-fs error (device loop0): __ext4_get_inode_loc:4444: comm kworker/u4:1: Invalid inode table block 0 in block_group 0
EXT4-fs (loop0): Delayed block allocation failed for inode 19 at logical offset 0 with max blocks 16 with error 28
EXT4-fs (loop0): This should not happen!! Data will be lost

EXT4-fs (loop0): Total free blocks count 0
EXT4-fs (loop0): Free/Dirty block details
EXT4-fs (loop0): free_blocks=0
EXT4-fs (loop0): dirty_blocks=0
EXT4-fs (loop0): Block reservation details
EXT4-fs (loop0): i_reserved_data_blocks=0
EXT4-fs error (device loop0): __ext4_get_inode_loc:4444: comm kworker/u4:1: Invalid inode table block 0 in block_group 0
EXT4-fs error (device loop0): __ext4_get_inode_loc:4444: comm kworker/u4:1: Invalid inode table block 0 in block_group 0
EXT4-fs (loop0): Delayed block allocation failed for inode 19 at logical offset 0 with max blocks 16 with error 28
EXT4-fs (loop0): This should not happen!! Data will be lost

EXT4-fs (loop0): Total free blocks count 0
EXT4-fs (loop0): Free/Dirty block details
EXT4-fs (loop0): free_blocks=0
EXT4-fs (loop0): dirty_blocks=0
EXT4-fs (loop0): Block reservation details
EXT4-fs (loop0): i_reserved_data_blocks=0
EXT4-fs error (device loop0): __ext4_get_inode_loc:4444: comm kworker/u4:1: Invalid inode table block 0 in block_group 0
EXT4-fs error (device loop0): __ext4_get_inode_loc:4444: comm kworker/u4:1: Invalid inode table block 0 in block_group 0
EXT4-fs error (device loop0): ext4_ext_split:1073: inode #19: comm kworker/u4:1: p_ext > EXT_MAX_EXTENT!
EXT4-fs (loop0): Delayed block allocation failed for inode 19 at logical offset 0 with max blocks 16 with error 117
EXT4-fs (loop0): This should not happen!! Data will be lost

EXT4-fs error (device loop0): __ext4_get_inode_loc:4444: comm kworker/u4:1: Invalid inode table block 0 in block_group 0
EXT4-fs error (device loop0): __ext4_get_inode_loc:4444: comm kworker/u4:1: Invalid inode table block 0 in block_group 0
EXT4-fs (loop0): Delayed block allocation failed for inode 19 at logical offset 0 with max blocks 16 with error 28
EXT4-fs (loop0): This should not happen!! Data will be lost

EXT4-fs (loop0): Total free blocks count 0
EXT4-fs (loop0): Free/Dirty block details
EXT4-fs (loop0): free_blocks=0
EXT4-fs (loop0): dirty_blocks=0
EXT4-fs (loop0): Block reservation details
EXT4-fs (loop0): i_reserved_data_blocks=0
EXT4-fs error (device loop0): __ext4_get_inode_loc:4444: comm kworker/u4:1: Invalid inode table block 0 in block_group 0
EXT4-fs error (device loop0): __ext4_get_inode_loc:4444: comm kworker/u4:1: Invalid inode table block 0 in block_group 0
EXT4-fs error (device loop0): ext4_map_blocks:740: inode #19: comm kworker/u4:1: lblock 0 mapped to illegal pblock 0 (length 3)
EXT4-fs (loop0): Delayed block allocation failed for inode 19 at logical offset 0 with max blocks 3 with error 117
EXT4-fs (loop0): This should not happen!! Data will be lost

EXT4-fs error (device loop0): __ext4_get_inode_loc:4444: comm kworker/u4:1: Invalid inode table block 0 in block_group 0
EXT4-fs error (device loop0): __ext4_get_inode_loc:4444: comm kworker/u4:1: Invalid inode table block 0 in block_group 0
EXT4-fs error (device loop0): ext4_ext_split:1073: inode #19: comm kworker/u4:1: p_ext > EXT_MAX_EXTENT!
EXT4-fs (loop0): Delayed block allocation failed for inode 19 at logical offset 0 with max blocks 16 with error 117
EXT4-fs (loop0): This should not happen!! Data will be lost

EXT4-fs error (device loop0): __ext4_get_inode_loc:4444: comm kworker/u4:1: Invalid inode table block 0 in block_group 0
EXT4-fs error (device loop0): __ext4_get_inode_loc:4444: comm kworker/u4:1: Invalid inode table block 0 in block_group 0
EXT4-fs error (device loop0): ext4_map_blocks:740: inode #19: block 96757035827499: comm kworker/u4:1: lblock 0 mapped to illegal pblock 96757035827499 (length 13)
EXT4-fs (loop0): Delayed block allocation failed for inode 19 at logical offset 0 with max blocks 13 with error 117
EXT4-fs (loop0): This should not happen!! Data will be lost

EXT4-fs error (device loop0): __ext4_get_inode_loc:4444: comm kworker/u4:1: Invalid inode table block 0 in block_group 0