kernel BUG in ext4_split_extent_at

Status: auto-obsoleted due to no activity on 2026/09/22 21:28
Reported-by: syzbot+2bca6fe615e588a77cb9@syzkaller.appspotmail.com
First crash: 227d, last: 212d
Fix bisection: failed (error log, bisect log)
  
▶ ▼ Bug presence (1)
Date Name Commit Repro Result
2026/09/22 upstream (ToT) f0100363d8c3 C Didn't crash
▶ ▼ Similar bugs (8)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream kernel BUG in ext4_split_extent_at ext4 -1 1 1719d 1715d 0/29 auto-closed as invalid on 2022/06/08 01:32
android-5-10 kernel BUG in ext4_split_extent_at -1 syz, C error error 25 62d 1233d 0/2 upstream: reported C repro on 2023/06/09 00:07
upstream kernel BUG in ext4_split_extent_at (2) ext4 -1 syz, C error done 3 1034d 1229d 25/29 fixed on 2024/01/30 15:47
android-6-1 kernel BUG in ext4_split_extent_at (3) -1 2 212d 229d 0/2 auto-obsoleted due to no activity on 2026/06/24 18:09
android-6-1 kernel BUG in ext4_split_extent_at missing-backport origin:upstream -1 syz, C error error 1 772d 1233d 0/2 auto-obsoleted due to no activity on 2024/12/21 09:12
android-6-1 kernel BUG in ext4_split_extent_at (2) origin:lts -1 syz, C done 1 466d 466d 0/2 auto-obsoleted due to no activity on 2025/10/22 23:15
upstream kernel BUG in ext4_split_extent_at (3) ext4 -1 3 470d 485d 0/29 auto-obsoleted due to no activity on 2025/10/19 20:03
android-5-15 kernel BUG in ext4_split_extent_at missing-backport origin:lts -1 syz, C error error 12 85d 513d 0/2 upstream: reported C repro on 2025/05/29 02:28

Sample crash report:
EXT4-fs (loop1): mounted filesystem without journal. Quota mode: writeback.
------------[ cut here ]------------
kernel BUG at fs/ext4/extents.c:3200!
Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 5134 Comm: syz.1.263 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_split_extent_at+0xd78/0xdcc fs/ext4/extents.c:3200
lr : ext4_split_extent_at+0xd78/0xdcc fs/ext4/extents.c:3200
sp : ffff800023df7380
x29: ffff800023df7480 x28: 0000000000000041 x27: dfff800000000000
x26: ffff0000f7733c18 x25: ffff0000f7733c1c x24: 0000000000000002
x23: 0000000000000000 x22: ffff0000f7733c1e x21: 1fffe0001eee6783
x20: 0000000000000000 x19: 0000000000000000 x18: 0000000000000000
x17: ffff80001835a000 x16: ffff8000082d7db8 x15: ffff8000089f004c
x14: 0000000000000002 x13: 1fffe00019450d88 x12: 0000000000080000
x11: 0000000000004427 x10: ffff800022489000 x9 : ffff800008d347d4
x8 : 0000000000004428 x7 : 0000000000000000 x6 : ffff800008059a4c
x5 : 0000000050000028 x4 : 0000000000000000 x3 : 0000000000000041
x2 : ffff0000ca286c00 x1 : 0000000000000000 x0 : 0000000000000041
Call trace:
 ext4_split_extent_at+0xd78/0xdcc fs/ext4/extents.c:3200
 ext4_force_split_extent_at fs/ext4/extents.c:342 [inline]
 ext4_ext_remove_space+0x63c/0x3ac4 fs/ext4/extents.c:2892
 ext4_punch_hole+0x694/0xb58 fs/ext4/inode.c:4141
 ext4_fallocate+0x224/0x1abc fs/ext4/extents.c:4818
 vfs_fallocate+0x4a4/0x5f4 fs/open.c:323
 ioctl_preallocate+0x20c/0x2b4 fs/ioctl.c:290
 file_ioctl fs/ioctl.c:-1 [inline]
 do_vfs_ioctl+0x1874/0x2100 fs/ioctl.c:849
 __do_sys_ioctl fs/ioctl.c:868 [inline]
 __se_sys_ioctl fs/ioctl.c:856 [inline]
 __arm64_sys_ioctl+0xe4/0x1c8 fs/ioctl.c:856
 __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: aa1303e0 97eecb30 17ffff2e 97dddb72 (d4210000) 
---[ end trace 0000000000000000 ]---

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/03/26 21:19 linux-6.1.y 1989cd3d56e2 766b6434 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 kernel BUG in ext4_split_extent_at
2026/03/11 10:04 linux-6.1.y f2ddafa93a25 86914af9 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-6-1-kasan-arm64 kernel BUG in ext4_split_extent_at
2026/03/11 06:34 linux-6.1.y f2ddafa93a25 86914af9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 kernel BUG in ext4_split_extent_at
* Struck through repros no longer work on HEAD.