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WARNING in iomap_write_begin

Status: upstream: reported C repro on 2024/08/13 08:14
Subsystems: xfs iomap
[Documentation on labels]
Reported-by: syzbot+296b1c84b9cbf306e5a0@syzkaller.appspotmail.com
Fix commit: vfs: Fix implicit conversion problem when testing overflow case
Patched on: [ci-upstream-linux-next-kasan-gce-root], missing on: [ci-qemu-gce-upstream-auto ci-qemu-native-arm64-kvm ci-qemu-upstream ci-qemu-upstream-386 ci-qemu2-arm32 ci-qemu2-arm64 ci-qemu2-arm64-compat ci-qemu2-arm64-mte ci-qemu2-riscv64 ci-snapshot-upstream-root ci-upstream-bpf-kasan-gce ci-upstream-bpf-next-kasan-gce ci-upstream-gce-arm64 ci-upstream-gce-leak ci-upstream-kasan-badwrites-root ci-upstream-kasan-gce ci-upstream-kasan-gce-386 ci-upstream-kasan-gce-root ci-upstream-kasan-gce-selinux-root ci-upstream-kasan-gce-smack-root ci-upstream-kmsan-gce-386-root ci-upstream-kmsan-gce-root ci-upstream-net-kasan-gce ci-upstream-net-this-kasan-gce ci-upstream-rust-kasan-gce ci2-upstream-fs ci2-upstream-kcsan-gce ci2-upstream-usb]
First crash: 686d, last: 668d
Cause bisection: failed (error log, bisect log)
  
▶ ▼ ✨ AI Jobs (5)
ID Workflow Result Correct Bug Created Started Finished Revision Error
f28f1cc0-b3eb-4a10-8475-3694b88283e3 assessment-security 💥 WARNING in iomap_write_begin 2026/06/18 07:08 2026/06/18 07:08 2026/06/18 07:37 b62b3ded1759f79b37600c5ffe2b0a81b919b0b0 
failed to run ["make" "KERNELVERSION=syzkaller" "KERNELRELEASE=syzkaller" "LOCALVERSION=-syzkaller" "-j" "32" "ARCH=x86_64" "CC=ccache clang" "LD=ld.lld" "O=/app/workdir/cache/build/3ddeeac7765fc37911...
truncated to first 200 bytes; open job for full error
05c886ca-2428-428e-a7eb-d8376844649d assessment-security 💥 WARNING in iomap_write_begin 2026/06/10 02:55 2026/06/10 02:55 2026/06/10 03:23 c36c07f6c1f2230a36374cbd22235f635e8f9284 
failed to run ["make" "KERNELVERSION=syzkaller" "KERNELRELEASE=syzkaller" "LOCALVERSION=-syzkaller" "-j" "32" "ARCH=x86_64" "CC=ccache clang" "LD=ld.lld" "O=/app/workdir/cache/build/3ddeeac7765fc37911...
truncated to first 200 bytes; open job for full error
7cf51131-09b8-4a20-93a8-98780d683ec0 assessment-security 💥 WARNING in iomap_write_begin 2026/06/04 05:32 2026/06/04 05:32 2026/06/04 05:49 62fe15281f5011cd203d8845b8767b10e7443aa5 
failed to run ["make" "KERNELVERSION=syzkaller" "KERNELRELEASE=syzkaller" "LOCALVERSION=-syzkaller" "-j" "32" "ARCH=x86_64" "CC=ccache clang" "LD=ld.lld" "O=/app/workdir/cache/build/3ddeeac7765fc37911...
truncated to first 200 bytes; open job for full error
2243c306-fb3b-43fa-b80d-a5c8f4ccd11f assessment-security 💥 WARNING in iomap_write_begin 2026/06/02 00:52 2026/06/02 00:52 2026/06/02 01:22 386cc6dacdf7e3ebce9507beed6755d7e999554d 
failed to run ["make" "KERNELVERSION=syzkaller" "KERNELRELEASE=syzkaller" "LOCALVERSION=-syzkaller" "-j" "32" "ARCH=x86_64" "CC=ccache clang" "LD=ld.lld" "O=/app/workdir/cache/build/3ddeeac7765fc37911...
truncated to first 200 bytes; open job for full error
49c87ece-21d2-4ceb-a590-4adad302eea1 assessment-security 💥 WARNING in iomap_write_begin 2026/05/20 08:50 2026/05/20 08:50 2026/05/20 09:12 0909d65fc692e54fa1900b68b476e89207bc7f34 
failed to run ["make" "KERNELVERSION=syzkaller" "KERNELRELEASE=syzkaller" "LOCALVERSION=-syzkaller" "-j" "32" "ARCH=x86_64" "CC=ccache clang" "LD=ld.lld" "O=/app/workdir/cache/build/3ddeeac7765fc37911...
truncated to first 200 bytes; open job for full error
▶ ▼ Discussions (7)
Title Replies (including bot) Last reply
[PATCH v2] xfs: do not unshare any blocks beyond eof 4 (4) 2024/09/29 23:23
[PATCH 2/3] vfs: Fix implicit conversion problem when testing overflow case 6 (6) 2024/09/26 09:06
[PATCH 1/3] xfs: Do not unshare ranges beyond EOF 3 (3) 2024/09/20 16:17
[PATCH 1/2] iomap: Do not unshare exents beyond EOF 13 (13) 2024/09/17 20:39
[PATCH 2/2] vfs: Fix implicit conversion problem when testing overflow case 2 (2) 2024/09/05 12:15
[PATCH] iomap: clean preallocated blocks in iomap_end() when 0 bytes was written. 4 (4) 2024/09/04 07:51
[syzbot] [iomap?] [xfs?] WARNING in iomap_write_begin 9 (14) 2024/09/02 05:28
▶ ▼ Last patch testing requests (9)
Created Duration User Patch Repo Result
2024/09/02 05:05 22m sunjunchao2870@gmail.com patch git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git ee9a43b7cfe2 OK log
2024/08/30 11:31 20m sunjunchao2870@gmail.com patch git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git ee9a43b7cfe2 OK log
2024/08/30 09:48 12m sunjunchao2870@gmail.com patch git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git ee9a43b7cfe2 report log
2024/08/27 11:41 11m nogikh@google.com upstream report log
2024/08/23 23:31 13m retest repro upstream report log
2024/08/23 23:31 11m retest repro upstream report log
2024/08/23 23:31 11m retest repro upstream report log
2024/08/23 23:31 1h00m retest repro upstream report log
2024/08/23 23:31 12m retest repro upstream report log

Sample crash report:
------------[ cut here ]------------
WARNING: CPU: 1 PID: 5222 at fs/iomap/buffered-io.c:727 __iomap_write_begin fs/iomap/buffered-io.c:727 [inline]
WARNING: CPU: 1 PID: 5222 at fs/iomap/buffered-io.c:727 iomap_write_begin+0x13f0/0x16f0 fs/iomap/buffered-io.c:830
Modules linked in:
CPU: 1 UID: 0 PID: 5222 Comm: syz-executor247 Not tainted 6.11.0-rc2-syzkaller-00111-gee9a43b7cfe2 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/27/2024
RIP: 0010:__iomap_write_begin fs/iomap/buffered-io.c:727 [inline]
RIP: 0010:iomap_write_begin+0x13f0/0x16f0 fs/iomap/buffered-io.c:830
Code: b5 0d 01 90 48 c7 c7 a0 54 fa 8b e8 da 19 2b ff 90 0f 0b 90 90 e9 74 ef ff ff e8 5b f1 68 ff e9 4b f6 ff ff e8 51 f1 68 ff 90 <0f> 0b 90 bb fb ff ff ff e9 e9 fe ff ff e8 3e f1 68 ff 90 0f 0b 90
RSP: 0018:ffffc90003a577c0 EFLAGS: 00010293
RAX: ffffffff822a858f RBX: 0000000000000080 RCX: ffff888023080000
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 0000000000000000
RBP: ffffc90003a57a50 R08: ffffffff822a8294 R09: 1ffff11029263f69
R10: dffffc0000000000 R11: ffffed1029263f6a R12: ffffc90003a579b0
R13: ffffc90003a57bf0 R14: ffffc90003a57990 R15: 0000000000000800
FS:  000055555f8fc480(0000) GS:ffff8880b9300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020001000 CR3: 0000000079b06000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 iomap_unshare_iter fs/iomap/buffered-io.c:1351 [inline]
 iomap_file_unshare+0x460/0x780 fs/iomap/buffered-io.c:1391
 xfs_reflink_unshare+0x173/0x5f0 fs/xfs/xfs_reflink.c:1681
 xfs_file_fallocate+0x6be/0xa50 fs/xfs/xfs_file.c:997
 vfs_fallocate+0x553/0x6c0 fs/open.c:334
 ksys_fallocate fs/open.c:357 [inline]
 __do_sys_fallocate fs/open.c:365 [inline]
 __se_sys_fallocate fs/open.c:363 [inline]
 __x64_sys_fallocate+0xbd/0x110 fs/open.c:363
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2d716a6899
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 17 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd620c3d18 EFLAGS: 00000246 ORIG_RAX: 000000000000011d
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f2d716a6899
RDX: 0000000000000000 RSI: 0000000000000040 RDI: 0000000000000006
RBP: 0000000000000000 R08: 0700000000000000 R09: 0700000000000000
R10: 0000000000002000 R11: 0000000000000246 R12: 00007ffd620c3d60
R13: 00007ffd620c3fe8 R14: 431bde82d7b634db R15: 00007f2d716ef03b
 </TASK>

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/08/09 21:49 upstream ee9a43b7cfe2 a83d9288 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-upstream-fs WARNING in iomap_write_begin
2024/08/09 19:50 upstream ee9a43b7cfe2 a83d9288 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-upstream-fs WARNING in iomap_write_begin
2024/08/09 18:16 upstream ee9a43b7cfe2 a83d9288 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-upstream-fs WARNING in iomap_write_begin
2024/08/09 16:37 upstream ee9a43b7cfe2 a83d9288 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-upstream-fs WARNING in iomap_write_begin
2024/08/09 14:52 upstream ee9a43b7cfe2 a83d9288 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-upstream-fs WARNING in iomap_write_begin
2024/08/09 08:10 upstream cf6d429eb656 61405512 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in iomap_write_begin
* Struck through repros no longer work on HEAD.