kernel BUG in ext4_es_cache_extent

Status: upstream: reported syz repro on 2026/03/11 08:55
Reported-by: syzbot+521e748b7c74a2019319@syzkaller.appspotmail.com
First crash: 146d, last: 146d
Fix bisection: failed (error log, bisect log)
  
▶ ▼ Bug presence (1)
Date Name Commit Repro Result
2026/07/01 upstream (ToT) 665159e24674 syz Failed due to an error; will retry later
▶ ▼ Similar bugs (9)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream kernel BUG in ext4_es_cache_extent ext4 -1 syz, C inconclusive 6 1281d 1640d 22/29 fixed on 2023/02/24 13:50
android-54 kernel BUG in ext4_es_cache_extent ext4 -1 syz, C 16 747d 1437d 0/2 auto-obsoleted due to no activity on 2024/10/26 14:37
upstream kernel BUG in ext4_es_cache_extent (4) prio:high ext4 -1 syz, C error error 15 132d 176d 0/29 upstream: reported C repro on 2026/02/09 02:08
android-5-15 kernel BUG in ext4_es_cache_extent origin:lts -1 syz, C error 7 151d 163d 0/2 upstream: reported C repro on 2026/02/22 03:30
android-5-10 kernel BUG in ext4_es_cache_extent -1 syz, C error 1 1437d 1437d 0/2 closed as invalid on 2022/09/13 19:49
upstream kernel BUG in ext4_es_cache_extent (3) ext4 -1 syz, C 4 320d 334d 29/29 fixed on 2025/11/18 08:45
android-5-10 kernel BUG in ext4_es_cache_extent (2) -1 syz, C done 9 114d 291d 0/2 upstream: reported C repro on 2025/10/16 22:01
android-6-1 kernel BUG in ext4_es_cache_extent origin:upstream missing-backport -1 syz, C error 11 104d 151d 0/2 upstream: reported C repro on 2026/03/06 16:01
upstream kernel BUG in ext4_es_cache_extent (2) ext4 -1 1 558d 554d 0/29 auto-obsoleted due to no activity on 2025/05/03 18:51

Sample crash report:
------------[ cut here ]------------
kernel BUG at fs/ext4/extents_status.c:967!
Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 4573 Comm: syz.0.32 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/26/2026
pstate: 82400005 (Nzcv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : ext4_es_cache_extent+0x630/0x6c4 fs/ext4/extents_status.c:967
lr : ext4_es_cache_extent+0x630/0x6c4 fs/ext4/extents_status.c:967
sp : ffff8000214b6c40
x29: ffff8000214b6ce0 x28: ffff0000eabae4d8 x27: dfff800000000000
x26: ffff8000214b6c40 x25: ffff700004296d88 x24: 0000000000000001
x23: ffff80001520d160 x22: 0000000000000002 x21: 0000000000000110
x20: 0000000000000114 x19: ffff0000e2a934d8 x18: ffff800011b8bf60
x17: 1fffe00033eac97e x16: ffff8000082ef8dc x15: ffff80001520d000
x14: 0000000000000003 x13: 1ffff00004296d8c x12: 0000000000ff0100
x11: ff00800008d3b5f8 x10: 0000000000000000 x9 : ffff800008d3b5f8
x8 : ffff0000d3ff0000 x7 : 0000000000000000 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000000 x3 : 0000000000000010
x2 : 0000000000000008 x1 : 0000000000000114 x0 : 0000000000000110
Call trace:
 ext4_es_cache_extent+0x630/0x6c4 fs/ext4/extents_status.c:967
 ext4_cache_extents fs/ext4/extents.c:536 [inline]
 __read_extent_tree_block+0x450/0x840 fs/ext4/extents.c:583
 ext4_find_extent+0x71c/0xb68 fs/ext4/extents.c:936
 ext4_ext_map_blocks+0x268/0x56f4 fs/ext4/extents.c:4172
 ext4_map_blocks+0x860/0x1778 fs/ext4/inode.c:679
 _ext4_get_block+0x19c/0x4d8 fs/ext4/inode.c:822
 ext4_get_block_unwritten+0x3c/0x110 fs/ext4/inode.c:855
 ext4_block_write_begin+0x50c/0x10e4 fs/ext4/inode.c:1124
 ext4_write_begin+0x5f4/0x131c fs/ext4/ext4_jbd2.h:-1
 ext4_da_write_begin+0x348/0x990 fs/ext4/inode.c:3000
 generic_perform_write+0x234/0x4f4 mm/filemap.c:3862
 ext4_buffered_write_iter+0x2c4/0x528 fs/ext4/file.c:285
 ext4_file_write_iter+0x18c/0x1574 fs/ext4/file.c:-1
 call_write_iter include/linux/fs.h:2265 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x3ec/0x7f0 fs/read_write.c:584
 ksys_pwrite64 fs/read_write.c:699 [inline]
 __do_sys_pwrite64 fs/read_write.c:709 [inline]
 __se_sys_pwrite64 fs/read_write.c:706 [inline]
 __arm64_sys_pwrite64+0x174/0x20c fs/read_write.c:706
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2b4 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x58/0x130 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
Code: b40004f6 97ddbf33 17fffebd 97ddbf31 (d4210000) 
---[ end trace 0000000000000000 ]---

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/03/11 08:54 linux-6.1.y f2ddafa93a25 86914af9 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-6-1-kasan-arm64 kernel BUG in ext4_es_cache_extent
* Struck through repros no longer work on HEAD.