EXT4-fs (loop1): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: none.
==================================================================
BUG: KASAN: use-after-free in ext4_ext_rm_leaf fs/ext4/extents.c:2632 [inline]
BUG: KASAN: use-after-free in ext4_ext_remove_space+0x3ea6/0x4140 fs/ext4/extents.c:2966
Read of size 4 at addr ffff888048300c18 by task syz.1.2193/12743

CPU: 1 UID: 0 PID: 12743 Comm: syz.1.2193 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0x156/0x4c9 mm/kasan/report.c:482
 kasan_report+0xdf/0x1e0 mm/kasan/report.c:595
 ext4_ext_rm_leaf fs/ext4/extents.c:2632 [inline]
 ext4_ext_remove_space+0x3ea6/0x4140 fs/ext4/extents.c:2966
 ext4_ext_truncate+0x23c/0x2f0 fs/ext4/extents.c:4539
 ext4_truncate+0xf04/0x1280 fs/ext4/inode.c:4564
 ext4_setattr+0x1a2c/0x2660 fs/ext4/inode.c:5956
 notify_change+0xb25/0x1330 fs/attr.c:556
 do_truncate+0x1df/0x240 fs/open.c:68
 handle_truncate fs/namei.c:4279 [inline]
 do_open fs/namei.c:4675 [inline]
 path_openat+0x2a55/0x31a0 fs/namei.c:4830
 do_file_open+0x20e/0x430 fs/namei.c:4859
 do_sys_openat2+0x10d/0x1e0 fs/open.c:1366
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_open fs/open.c:1380 [inline]
 __se_sys_open fs/open.c:1376 [inline]
 __x64_sys_open+0xfe/0x1d0 fs/open.c:1376
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f787299c629
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f7873854028 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007f7872c15fa0 RCX: 00007f787299c629
RDX: 00000000000000dc RSI: 000000000004827e RDI: 0000200000000200
RBP: 00007f7872a32b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7872c16038 R14: 00007f7872c15fa0 R15: 00007fffc160d2b8
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xc11 pfn:0x48300
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f0(buddy)
raw: 00fff00000000000 ffffea00010e6008 ffffea0000e9e008 0000000000000000
raw: 0000000000000c11 0000000000000006 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 12263, tgid 12262 (syz.2.2037), ts 778472922506, free_ts 780567703250
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x153/0x170 mm/page_alloc.c:1889
 prep_new_page mm/page_alloc.c:1897 [inline]
 get_page_from_freelist+0x111d/0x3140 mm/page_alloc.c:3962
 __alloc_frozen_pages_noprof+0x27c/0x2ba0 mm/page_alloc.c:5250
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2485
 folio_alloc_mpol_noprof+0x36/0x340 mm/mempolicy.c:2504
 shmem_alloc_folio+0x135/0x160 mm/shmem.c:1930
 shmem_alloc_and_add_folio+0x371/0xd40 mm/shmem.c:1972
 shmem_get_folio_gfp+0x6ab/0x1900 mm/shmem.c:2567
 shmem_get_folio mm/shmem.c:2673 [inline]
 shmem_write_begin+0x1a4/0x420 mm/shmem.c:3327
 generic_perform_write+0x292/0xa40 mm/filemap.c:4314
 shmem_file_write_iter+0x10e/0x140 mm/shmem.c:3502
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x6ac/0x1070 fs/read_write.c:688
 ksys_write+0x12a/0x250 fs/read_write.c:740
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 5825 tgid 5825 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1433 [inline]
 free_unref_folios+0xaea/0x1790 mm/page_alloc.c:3040
 folios_put_refs+0x53c/0x840 mm/swap.c:1002
 folio_batch_release include/linux/pagevec.h:101 [inline]
 shmem_undo_range+0x5e5/0x1570 mm/shmem.c:1149
 shmem_truncate_range mm/shmem.c:1277 [inline]
 shmem_evict_inode+0x39e/0xbd0 mm/shmem.c:1407
 evict+0x3c2/0xad0 fs/inode.c:846
 iput_final fs/inode.c:1966 [inline]
 iput.part.0+0x605/0xf50 fs/inode.c:2015
 iput+0x35/0x40 fs/inode.c:1981
 dentry_unlink_inode+0x2a1/0x490 fs/dcache.c:467
 __dentry_kill+0x1d0/0x600 fs/dcache.c:670
 finish_dput+0x76/0x480 fs/dcache.c:879
 dput.part.0+0x456/0x570 fs/dcache.c:928
 dput+0x1f/0x30 fs/dcache.c:920
 __fput+0x519/0xb40 fs/file_table.c:477
 task_work_run+0x150/0x240 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
 exit_to_user_mode_loop+0x100/0x4a0 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
 do_syscall_64+0x67c/0xf80 arch/x86/entry/syscall_64.c:100

Memory state around the buggy address:
 ffff888048300b00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888048300b80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888048300c00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                            ^
 ffff888048300c80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888048300d00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
==================================================================
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_rm_leaf fs/ext4/extents.c:2633 [inline]
BUG: KASAN: use-after-free in ext4_ext_remove_space+0x3e99/0x4140 fs/ext4/extents.c:2966
Read of size 2 at addr ffff888048300c1c by task syz.1.2193/12743

CPU: 0 UID: 0 PID: 12743 Comm: syz.1.2193 Tainted: G    B        L      syzkaller #0 PREEMPT(full) 
Tainted: [B]=BAD_PAGE, [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0x156/0x4c9 mm/kasan/report.c:482
 kasan_report+0xdf/0x1e0 mm/kasan/report.c:595
 ext4_ext_get_actual_len fs/ext4/ext4_extents.h:205 [inline]
 ext4_ext_rm_leaf fs/ext4/extents.c:2633 [inline]
 ext4_ext_remove_space+0x3e99/0x4140 fs/ext4/extents.c:2966
 ext4_ext_truncate+0x23c/0x2f0 fs/ext4/extents.c:4539
 ext4_truncate+0xf04/0x1280 fs/ext4/inode.c:4564
 ext4_setattr+0x1a2c/0x2660 fs/ext4/inode.c:5956
 notify_change+0xb25/0x1330 fs/attr.c:556
 do_truncate+0x1df/0x240 fs/open.c:68
 handle_truncate fs/namei.c:4279 [inline]
 do_open fs/namei.c:4675 [inline]
 path_openat+0x2a55/0x31a0 fs/namei.c:4830
 do_file_open+0x20e/0x430 fs/namei.c:4859
 do_sys_openat2+0x10d/0x1e0 fs/open.c:1366
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_open fs/open.c:1380 [inline]
 __se_sys_open fs/open.c:1376 [inline]
 __x64_sys_open+0xfe/0x1d0 fs/open.c:1376
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f787299c629
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f7873854028 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007f7872c15fa0 RCX: 00007f787299c629
RDX: 00000000000000dc RSI: 000000000004827e RDI: 0000200000000200
RBP: 00007f7872a32b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7872c16038 R14: 00007f7872c15fa0 R15: 00007fffc160d2b8
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xc11 pfn:0x48300
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f0(buddy)
raw: 00fff00000000000 ffffea00010e6008 ffffea0000e9e008 0000000000000000
raw: 0000000000000c11 0000000000000006 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 12263, tgid 12262 (syz.2.2037), ts 778472922506, free_ts 780567703250
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x153/0x170 mm/page_alloc.c:1889
 prep_new_page mm/page_alloc.c:1897 [inline]
 get_page_from_freelist+0x111d/0x3140 mm/page_alloc.c:3962
 __alloc_frozen_pages_noprof+0x27c/0x2ba0 mm/page_alloc.c:5250
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2485
 folio_alloc_mpol_noprof+0x36/0x340 mm/mempolicy.c:2504
 shmem_alloc_folio+0x135/0x160 mm/shmem.c:1930
 shmem_alloc_and_add_folio+0x371/0xd40 mm/shmem.c:1972
 shmem_get_folio_gfp+0x6ab/0x1900 mm/shmem.c:2567
 shmem_get_folio mm/shmem.c:2673 [inline]
 shmem_write_begin+0x1a4/0x420 mm/shmem.c:3327
 generic_perform_write+0x292/0xa40 mm/filemap.c:4314
 shmem_file_write_iter+0x10e/0x140 mm/shmem.c:3502
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x6ac/0x1070 fs/read_write.c:688
 ksys_write+0x12a/0x250 fs/read_write.c:740
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 5825 tgid 5825 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1433 [inline]
 free_unref_folios+0xaea/0x1790 mm/page_alloc.c:3040
 folios_put_refs+0x53c/0x840 mm/swap.c:1002
 folio_batch_release include/linux/pagevec.h:101 [inline]
 shmem_undo_range+0x5e5/0x1570 mm/shmem.c:1149
 shmem_truncate_range mm/shmem.c:1277 [inline]
 shmem_evict_inode+0x39e/0xbd0 mm/shmem.c:1407
 evict+0x3c2/0xad0 fs/inode.c:846
 iput_final fs/inode.c:1966 [inline]
 iput.part.0+0x605/0xf50 fs/inode.c:2015
 iput+0x35/0x40 fs/inode.c:1981
 dentry_unlink_inode+0x2a1/0x490 fs/dcache.c:467
 __dentry_kill+0x1d0/0x600 fs/dcache.c:670
 finish_dput+0x76/0x480 fs/dcache.c:879
 dput.part.0+0x456/0x570 fs/dcache.c:928
 dput+0x1f/0x30 fs/dcache.c:920
 __fput+0x519/0xb40 fs/file_table.c:477
 task_work_run+0x150/0x240 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
 exit_to_user_mode_loop+0x100/0x4a0 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
 do_syscall_64+0x67c/0xf80 arch/x86/entry/syscall_64.c:100

Memory state around the buggy address:
 ffff888048300b00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888048300b80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888048300c00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                            ^
 ffff888048300c80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888048300d00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================