kernel BUG in ext4_ext_insert_extent

Status: upstream: reported C repro on 2026/03/05 21:58
Reported-by: syzbot+e67f274f1d95b6782e59@syzkaller.appspotmail.com
First crash: 344d, last: 119d
Fix bisection: failed (error log, bisect log)
  
Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream kernel BUG in ext4_ext_insert_extent (2) prio:high ext4 -1 syz, C done error 38 172d 509d 0/29 upstream: reported C repro on 2025/04/11 16:16
android-54 kernel BUG in ext4_ext_insert_extent -1 1 1682d 1682d 0/2 auto-closed as invalid on 2022/05/24 20:39
upstream kernel BUG in ext4_ext_insert_extent ext4 -1 1 2008d 2004d 0/29 auto-closed as invalid on 2021/06/02 20:11
android-6-1 kernel BUG in ext4_ext_insert_extent origin:upstream missing-backport -1 syz error 9 155d 201d 0/2 premoderation: reported syz repro on 2026/02/13 16:13
android-5-15 kernel BUG in ext4_ext_insert_extent origin:upstream missing-backport -1 syz, C error 13 120d 207d 0/2 auto-obsoleted due to no activity on 2026/08/16 07:33
Last patch testing requests (10)
Created Duration User Patch Repo Result
2026/09/03 05:49 38m retest repro android13-5.10-lts no crash job log log
2026/09/03 05:49 17m retest repro android13-5.10-lts no crash job log log
2026/09/03 05:49 19m retest repro android13-5.10-lts no crash job log log
2026/09/03 05:49 11m retest repro android13-5.10-lts no crash job log log
2026/09/03 05:49 11m retest repro android13-5.10-lts no crash job log log
2026/08/25 16:09 13m retest repro android13-5.10-lts no crash job log log
2026/08/25 16:09 13m retest repro android13-5.10-lts no crash job log log
2026/08/25 16:09 15m retest repro android13-5.10-lts no crash job log log
2026/08/25 16:09 15m retest repro android13-5.10-lts no crash job log log
2026/08/25 16:09 15m retest repro android13-5.10-lts no crash job log log

Sample crash report:
------------[ cut here ]------------
kernel BUG at fs/ext4/extents.c:2135!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 1309 Comm: syz.3.53 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2025
RIP: 0010:ext4_ext_insert_extent+0x44fa/0x4530 fs/ext4/extents.c:2135
Code: ff ff 89 d9 80 e1 07 fe c1 38 c1 0f 8c 01 e9 ff ff 48 89 df e8 e7 03 d5 ff e9 f4 e8 ff ff e8 cd 16 9b ff 0f 0b e8 c6 16 9b ff <0f> 0b e8 bf 16 9b ff 0f 0b 89 d9 80 e1 07 80 c1 03 38 c1 0f 8c 43
RSP: 0000:ffffc900017463e0 EFLAGS: 00010293
RAX: ffffffff81c88f4a RBX: ffff88812d66c400 RCX: ffff88812de08000
RDX: 0000000000000000 RSI: 0000000000000015 RDI: 0000000000000015
RBP: ffffc90001746590 R08: dffffc0000000000 R09: ffffed1023822ce8
R10: ffffed1023822ce8 R11: 1ffff11023822ce7 R12: 0000000000000015
R13: 1ffff11025be1548 R14: ffff88812d66c454 R15: 0000000000000015
FS:  0000555557513500(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f3c0cdb2710 CR3: 000000011b890000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 ext4_ext_map_blocks+0x148f/0x5d40 fs/ext4/extents.c:4356
 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
 __filemap_fdatawrite_range+0x2bc/0x360 mm/filemap.c:427
 file_write_and_wait_range+0x8c/0x110 mm/filemap.c:766
 ext4_sync_file+0x1a9/0x9f0 fs/ext4/fsync.c:151
 vfs_fsync_range+0x190/0x1a0 fs/sync.c:202
 generic_write_sync include/linux/fs.h:2920 [inline]
 ext4_buffered_write_iter+0x59b/0x640 fs/ext4/file.c:278
 ext4_file_write_iter+0x536/0x1980 fs/ext4/file.c:-1
 __kernel_write+0x55a/0x910 fs/read_write.c:550
 dump_emit+0x240/0x360 fs/coredump.c:855
 dump_user_range+0x6a/0x1a0 fs/coredump.c:908
 elf_core_dump+0x278a/0x2bc0 fs/binfmt_elf.c:2290
 do_coredump+0x1ac9/0x27f0 fs/coredump.c:817
 get_signal+0xf23/0x12e0 kernel/signal.c:2779
 arch_do_signal_or_restart+0xbf/0x10f0 arch/x86/kernel/signal.c:805
 handle_signal_work kernel/entry/common.c:145 [inline]
 exit_to_user_mode_loop+0xa2/0xe0 kernel/entry/common.c:169
 exit_to_user_mode_prepare+0x76/0xa0 kernel/entry/common.c:199
 irqentry_exit_to_user_mode+0x9/0x10 kernel/entry/common.c:287
 irqentry_exit+0x12/0x60 kernel/entry/common.c:375
 exc_page_fault+0x67/0xc0 arch/x86/mm/fault.c:1487
 asm_exc_page_fault+0x1e/0x30 arch/x86/include/asm/idtentry.h:571
RIP: 0033:0x7fc766f95ec9
Code: Unable to access opcode bytes at RIP 0x7fc766f95e9f.
RSP: 002b:00007fffbbb71448 EFLAGS: 00010206
RAX: 0000000000000000 RBX: 00007fc7671ecfa0 RCX: 00007fc766f95ec9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000000000a000
RBP: 00007fc767018f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007fc7671ecfa0 R14: 00007fc7671ecfa0 R15: 0000000000000006
Modules linked in:
---[ end trace 9265e461e37306e3 ]---
RIP: 0010:ext4_ext_insert_extent+0x44fa/0x4530 fs/ext4/extents.c:2135
Code: ff ff 89 d9 80 e1 07 fe c1 38 c1 0f 8c 01 e9 ff ff 48 89 df e8 e7 03 d5 ff e9 f4 e8 ff ff e8 cd 16 9b ff 0f 0b e8 c6 16 9b ff <0f> 0b e8 bf 16 9b ff 0f 0b 89 d9 80 e1 07 80 c1 03 38 c1 0f 8c 43
RSP: 0000:ffffc900017463e0 EFLAGS: 00010293
RAX: ffffffff81c88f4a RBX: ffff88812d66c400 RCX: ffff88812de08000
RDX: 0000000000000000 RSI: 0000000000000015 RDI: 0000000000000015
RBP: ffffc90001746590 R08: dffffc0000000000 R09: ffffed1023822ce8
R10: ffffed1023822ce8 R11: 1ffff11023822ce7 R12: 0000000000000015
R13: 1ffff11025be1548 R14: ffff88812d66c454 R15: 0000000000000015
FS:  0000555557513500(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc766f95e9f CR3: 000000011b890000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Crashes (12):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/09/23 22:41 android13-5.10-lts 911f602c2237 e667a34f .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 kernel BUG in ext4_ext_insert_extent
2026/05/06 17:46 android13-5.10-lts 95a92a883bae 1dddfd3d .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 kernel BUG in ext4_ext_insert_extent
2026/03/07 02:47 android13-5.10-lts 9a301c292a32 5cb44a80 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 kernel BUG in ext4_ext_insert_extent
2026/03/07 02:02 android13-5.10-lts 9a301c292a32 5cb44a80 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 kernel BUG in ext4_ext_insert_extent
2026/03/05 21:56 android13-5.10-lts dad37bbb13a8 d20b04c8 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 kernel BUG in ext4_ext_insert_extent
2026/03/04 01:02 android13-5.10-lts dad37bbb13a8 4180d919 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 kernel BUG in ext4_ext_insert_extent
2026/03/04 00:19 android13-5.10-lts dad37bbb13a8 4180d919 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 kernel BUG in ext4_ext_insert_extent
2026/02/22 17:12 android13-5.10-lts e8b14e1cefe8 6e7b5511 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 kernel BUG in ext4_ext_insert_extent
2026/02/22 13:57 android13-5.10-lts e8b14e1cefe8 6e7b5511 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 kernel BUG in ext4_ext_insert_extent
2026/02/22 13:30 android13-5.10-lts e8b14e1cefe8 6e7b5511 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 kernel BUG in ext4_ext_insert_extent
2025/12/19 12:24 android13-5.10-lts e253c52bbdfc d6526ea3 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro #1 (corrupt fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-10 kernel BUG in ext4_ext_insert_extent
2025/09/23 23:01 android13-5.10-lts 911f602c2237 e667a34f .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 kernel BUG in ext4_ext_insert_extent
* Struck through repros no longer work on HEAD.