WARNING in ext4_iomap_begin (3)

Status: upstream: reported C repro on 2024/10/31 12:34
Subsystems: ext4
Labels: prio:high
[Documentation on labels]
Reported-by: syzbot+626aa13bf52efc3aa86e@syzkaller.appspotmail.com
First crash: 695d, last: 4h50m
Cause bisection: the issue happens on the oldest tested release (bisect log)
Crash: kernel BUG in ext4_write_inline_data (log)
Repro: C syz .config
  
Fix bisection: failed (error log, bisect log)
  
✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision
661fa805 assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ✅ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ WARNING in ext4_iomap_begin (3) 2026/05/25 19:00 2026/05/25 19:00 2026/05/25 20:12 c69befb3
3e1b45d4 patching 💥 WARNING in ext4_iomap_begin (3) 2026/05/21 20:54 2026/05/21 21:36 2026/05/21 21:43 d5742584
Discussions (4)
Title Replies (including bot) Last reply
[syzbot] Monthly ext4 report (Sep 2026) 0 (1) 2026/09/11 04:33
[syzbot] Monthly ext4 report (Aug 2026) 0 (1) 2026/08/11 04:32
[syzbot] Monthly ext4 report (Jul 2026) 0 (1) 2026/07/10 20:32
[syzbot] [ext4?] WARNING in ext4_iomap_begin (3) 0 (2) 2024/11/01 01:18
Similar bugs (10)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 WARNING in ext4_iomap_begin (2) origin:upstream -1 syz, C done 10 463d 548d 3/3 fixed on 2025/07/16 19:57
linux-6.6 WARNING in ext4_iomap_begin origin:upstream -1 syz, C error 8 7d14h 391d 0/2 upstream: reported C repro on 2025/08/27 01:08
linux-6.1 WARNING in ext4_iomap_begin -1 1 1154d 1154d 0/3 auto-obsoleted due to no activity on 2023/11/02 21:33
upstream WARNING in ext4_iomap_begin ext4 -1 syz, C inconclusive error 16 1503d 1531d 0/29 auto-obsoleted due to no activity on 2023/04/04 00:54
linux-6.1 WARNING in ext4_iomap_begin (3) -1 2 388d 393d 0/3 auto-obsoleted due to no activity on 2025/12/07 16:01
linux-6.1 WARNING in ext4_iomap_begin (5) origin:upstream -1 syz, C error 5 7d17h 58d 0/3 upstream: reported C repro on 2026/07/26 07:25
upstream WARNING in ext4_iomap_begin (2) ext4 -1 syz, C done 7 1078d 1193d 25/29 fixed on 2023/12/21 03:45
linux-5.15 WARNING in ext4_iomap_begin origin:upstream -1 syz, C done 8 470d 503d 3/3 fixed on 2025/07/14 10:31
linux-6.1 WARNING in ext4_iomap_begin (4) -1 1 221d 221d 0/3 auto-obsoleted due to no activity on 2026/05/23 23:17
linux-5.15 WARNING in ext4_iomap_begin (2) origin:upstream -1 syz, C error 12 9d22h 407d 0/3 upstream: reported C repro on 2025/08/11 00:02
Last patch testing requests (10)
Created Duration User Patch Repo Result
2026/07/23 17:34 22m retest repro upstream report log
2026/05/29 23:32 26m retest repro upstream log
2026/05/29 23:32 20m retest repro upstream log
2026/05/29 23:32 29m retest repro upstream log
2026/05/29 23:32 23m retest repro upstream log
2026/05/29 23:32 21m retest repro upstream log
2026/05/29 00:09 49m retest repro linux-next log
2026/05/28 23:54 52m retest repro linux-next log
2026/05/14 22:35 33m retest repro upstream report log
2026/05/14 17:09 22m retest repro upstream error
Fix bisection attempts (2)
Created Duration User Patch Repo Result
2026/06/14 05:51 42m bisect fix upstream error job log
2025/01/25 21:26 2h52m bisect fix upstream OK (0) job log log

Sample crash report:
------------[ cut here ]------------
ext4_has_inline_data(inode)
WARNING: fs/ext4/inode.c:3785 at ext4_iomap_begin+0x175b/0x1960 fs/ext4/inode.c:3785, CPU#0: syz.4.21/6073
Modules linked in:
CPU: 0 UID: 0 PID: 6073 Comm: syz.4.21 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
RIP: 0010:ext4_iomap_begin+0x175b/0x1960 fs/ext4/inode.c:3785
Code: 42 1c 10 48 3b 84 24 40 01 00 00 75 64 44 89 f0 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc e8 76 2d 44 ff 90 <0f> 0b 90 41 be de ff ff ff e9 b9 e9 ff ff 44 89 f9 80 e1 07 38 c1
RSP: 0018:ffffc9000433f100 EFLAGS: 00010293
RAX: ffffffff8281ad7a RBX: 0000000000000000 RCX: ffff88802eea3e00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc9000433f298 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffed100bfe38ed R12: ffff88805ff1c9c0
R13: 1ffff92000867e38 R14: 00000000000000d4 R15: ffff88805ff1cac2
FS:  00007f3923dee6c0(0000) GS:ffff888125c41000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2c64bded58 CR3: 0000000037f5a000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 iomap_iter+0x5f5/0xf80 fs/iomap/iter.c:110
 __iomap_dio_rw+0xcae/0x1de0 fs/iomap/direct-io.c:808
 iomap_dio_rw+0x45/0xb0 fs/iomap/direct-io.c:903
 ext4_dio_write_iter fs/ext4/file.c:592 [inline]
 ext4_file_write_iter+0x1902/0x1c90 fs/ext4/file.c:733
 iter_file_splice_write+0xa36/0x1240 fs/splice.c:736
 do_splice_from fs/splice.c:936 [inline]
 direct_splice_actor+0x104/0x160 fs/splice.c:1159
 splice_direct_to_actor+0x586/0xcc0 fs/splice.c:1103
 do_splice_direct_actor fs/splice.c:1202 [inline]
 do_splice_direct+0x19b/0x2a0 fs/splice.c:1228
 do_sendfile+0x540/0x7e0 fs/read_write.c:1371
 __do_sys_sendfile64 fs/read_write.c:1432 [inline]
 __se_sys_sendfile64+0x144/0x1a0 fs/read_write.c:1418
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f392478df99
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:00007f3923dee028 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f3924a15fa0 RCX: 00007f392478df99
RDX: 0000000000000000 RSI: 0000000000000005 RDI: 0000000000000004
RBP: 00007f3924824ec4 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000020fffe82 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f3924a16038 R14: 00007f3924a15fa0 R15: 00007ffcd2957d18
 </TASK>

Crashes (325):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/30 06:55 upstream fc46aed51f62 6ef5c1e2 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/07/27 18:06 upstream f5098b6bae76 aae9036b .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-upstream-fs WARNING in ext4_iomap_begin
2025/12/12 04:01 upstream d358e5254674 d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci-upstream-kasan-badwrites-root WARNING in ext4_iomap_begin
2025/10/29 08:32 upstream 8eefed8f65cc fd2207e7 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (clean fs)] ci2-upstream-fs WARNING in ext4_iomap_begin
2024/11/01 01:17 upstream 0fc810ae3ae1 96eb609f .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/01/26 03:17 upstream 023777797472 02bac031 .config console log report syz / log C [disk image (non-bootable)] [vmlinux] [kernel image] [mounted in repro #1 (corrupt fs)] [mounted in repro #2] ci-snapshot-upstream-root WARNING in ext4_iomap_begin
2025/02/23 20:33 upstream 27102b38b8ca d34966d1 .config console log report syz / log C [disk image (non-bootable)] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci-snapshot-upstream-root WARNING in ext4_iomap_begin
2026/02/23 22:50 linux-next d4906ae14a5f 305c0ec5 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (clean fs)] ci-upstream-linux-next-kasan-gce-root WARNING in ext4_iomap_begin
2026/08/18 07:24 upstream ff68e5f557f6 1e72964b .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-upstream-fs WARNING in ext4_iomap_begin
2025/10/24 21:25 upstream 6fab32bb6508 c0460fcd .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro (clean fs)] ci2-upstream-fs WARNING in ext4_iomap_begin
2024/11/11 10:59 upstream 2d5404caa8c7 0c4b1325 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-upstream-fs WARNING in ext4_iomap_begin
2024/11/11 07:31 upstream a9cda7c0ffed 6b856513 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/22 08:57 upstream f0100363d8c3 e12281bd .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/22 07:23 upstream f0100363d8c3 e12281bd .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/22 07:17 upstream f0100363d8c3 e12281bd .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/22 01:56 upstream f0100363d8c3 853b104b .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/20 10:54 upstream 518e5b794c06 853b104b .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/19 22:37 upstream 40288c9206c1 853b104b .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/19 16:51 upstream 40288c9206c1 853b104b .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/19 10:48 upstream 17e7b8eacf4c 853b104b .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/19 08:24 upstream 17e7b8eacf4c 853b104b .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/19 02:30 upstream 17e7b8eacf4c 853b104b .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/18 21:35 upstream 5dd1818b15d9 853b104b .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/18 18:00 upstream 5dd1818b15d9 853b104b .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/18 16:48 upstream 5dd1818b15d9 853b104b .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/18 15:07 upstream 5dd1818b15d9 853b104b .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/18 00:37 upstream 4982d3552a3b 8d7d05f1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/17 22:19 upstream 4982d3552a3b 8d7d05f1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/17 19:28 upstream 4982d3552a3b 8d7d05f1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/17 09:13 upstream 238650ef6c7c 95928915 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/17 04:48 upstream 238650ef6c7c 95928915 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/16 15:30 upstream 9b87fdc9af2f 12a0a44a .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/16 10:43 upstream 9b87fdc9af2f 12a0a44a .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/15 20:22 upstream f6e7b42bf05b 2daa4bb5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/15 18:25 upstream f6e7b42bf05b 2daa4bb5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/15 15:12 upstream 587858367581 2daa4bb5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/15 10:36 upstream 587858367581 81a27d1a .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/15 09:18 upstream 587858367581 81a27d1a .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/15 04:35 upstream 587858367581 81a27d1a .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/15 03:00 upstream 704340f1cd0d 81a27d1a .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/14 22:53 upstream 704340f1cd0d 81a27d1a .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/14 19:21 upstream 704340f1cd0d 81a27d1a .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/14 15:29 upstream 704340f1cd0d 81a27d1a .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/14 14:36 upstream 704340f1cd0d 81a27d1a .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/14 11:03 upstream 704340f1cd0d 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/14 09:01 upstream 704340f1cd0d 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/14 07:09 upstream d681d7ef617e 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/13 23:39 upstream d681d7ef617e 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/13 21:42 upstream d681d7ef617e 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/13 19:31 upstream d681d7ef617e 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/13 11:56 upstream 2f0c1cf72f46 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/13 05:41 upstream 2f0c1cf72f46 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/13 03:11 upstream 5225b8eec4c9 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/13 01:23 upstream 5225b8eec4c9 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/12 23:25 upstream 5225b8eec4c9 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in ext4_iomap_begin
2026/09/03 23:13 upstream 841e384b841a 6a988719 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root WARNING in ext4_iomap_begin
2026/07/27 15:54 upstream f5098b6bae76 4cb2b096 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root WARNING in ext4_iomap_begin
2025/05/07 12:37 upstream 0d8d44db295c 350f4ffc .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-upstream-fs WARNING in ext4_iomap_begin
2025/04/12 05:16 upstream e618ee89561b 0bd6db41 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-upstream-fs WARNING in ext4_iomap_begin
2025/09/13 10:42 upstream 22f20375f5b7 e2beed91 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in ext4_iomap_begin
2024/10/27 12:28 upstream 850925a8133c 65e8686b .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in ext4_iomap_begin
2026/08/29 22:53 linux-next e30626823a40 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root WARNING in ext4_iomap_begin
2026/09/13 16:43 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 5445d6419962 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 WARNING in ext4_iomap_begin
* Struck through repros no longer work on HEAD.