[syzbot] [iomap?] general protection fault in iomap_dio_bio_end_io

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: fe4d0dea039f Add linux-next specific files for 20251119
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=16bd7692580000
kernel config: https://syzkaller.appspot.com/x/.config?x=f20a6db7594dcad7
dashboard link: https://syzkaller.appspot.com/bug?extid=a2b9a4ed0d61b1efb3f5
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12db68b4580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=107c0514580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ce4f26d91a01/disk-fe4d0dea.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6c9b53acf521/vmlinux-fe4d0dea.xz
kernel image: https://storage.googleapis.com/syzbot-assets/64d37d01cd64/bzImage-fe4d0dea.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/004457158842/mount_1.gz
fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=133a1a12580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a2b9a4...@syzkaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000038: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x00000000000001c0-0x00000000000001c7]
CPU: 1 UID: 0 PID: 23 Comm: ksoftirqd/1 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:__queue_work+0xa4/0xf90 kernel/workqueue.c:2250
Code: 10 31 ff 89 ee e8 ac 24 37 00 85 ed 0f 85 9d 0c 00 00 e8 5f 20 37 00 4d 8d b5 c0 01 00 00 4c 89 f0 48 c1 e8 03 48 89 44 24 30 <0f> b6 04 18 84 c0 0f 85 c4 0c 00 00 4c 89 34 24 41 8b 2e 89 ee 81
RSP: 0018:ffffc900001d7868 EFLAGS: 00010002
RAX: 0000000000000038 RBX: dffffc0000000000 RCX: ffff88801d2d5b80
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffff8880777ed647 R09: 1ffff1100eefdac8
R10: dffffc0000000000 R11: ffffed100eefdac9 R12: 0000000000000008
R13: 0000000000000000 R14: 00000000000001c0 R15: 0000000000000200
FS: 0000000000000000(0000) GS:ffff888125fbc000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000073fc0000 CR4: 00000000003526f0
Call Trace:
<TASK>
queue_work_on+0x181/0x270 kernel/workqueue.c:2386
iomap_dio_bio_end_io+0xf4/0x1c0 fs/iomap/direct-io.c:222
blk_update_request+0x57e/0xe60 block/blk-mq.c:1006
blk_mq_end_request+0x3e/0x70 block/blk-mq.c:1168
blk_complete_reqs block/blk-mq.c:1243 [inline]
blk_done_softirq+0x10a/0x160 block/blk-mq.c:1248
handle_softirqs+0x27d/0x880 kernel/softirq.c:626
run_ksoftirqd+0x9b/0x100 kernel/softirq.c:1067
smpboot_thread_fn+0x542/0xa60 kernel/smpboot.c:160
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__queue_work+0xa4/0xf90 kernel/workqueue.c:2250
Code: 10 31 ff 89 ee e8 ac 24 37 00 85 ed 0f 85 9d 0c 00 00 e8 5f 20 37 00 4d 8d b5 c0 01 00 00 4c 89 f0 48 c1 e8 03 48 89 44 24 30 <0f> b6 04 18 84 c0 0f 85 c4 0c 00 00 4c 89 34 24 41 8b 2e 89 ee 81
RSP: 0018:ffffc900001d7868 EFLAGS: 00010002
RAX: 0000000000000038 RBX: dffffc0000000000 RCX: ffff88801d2d5b80
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffff8880777ed647 R09: 1ffff1100eefdac8
R10: dffffc0000000000 R11: ffffed100eefdac9 R12: 0000000000000008
R13: 0000000000000000 R14: 00000000000001c0 R15: 0000000000000200
FS: 0000000000000000(0000) GS:ffff888125fbc000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000073fc0000 CR4: 00000000003526f0
----------------
Code disassembly (best guess), 1 bytes skipped:
0: 31 ff xor %edi,%edi
2: 89 ee mov %ebp,%esi
4: e8 ac 24 37 00 call 0x3724b5
9: 85 ed test %ebp,%ebp
b: 0f 85 9d 0c 00 00 jne 0xcae
11: e8 5f 20 37 00 call 0x372075
16: 4d 8d b5 c0 01 00 00 lea 0x1c0(%r13),%r14
1d: 4c 89 f0 mov %r14,%rax
20: 48 c1 e8 03 shr $0x3,%rax
24: 48 89 44 24 30 mov %rax,0x30(%rsp)
* 29: 0f b6 04 18 movzbl (%rax,%rbx,1),%eax <-- trapping instruction
2d: 84 c0 test %al,%al
2f: 0f 85 c4 0c 00 00 jne 0xcf9
35: 4c 89 34 24 mov %r14,(%rsp)
39: 41 8b 2e mov (%r14),%ebp
3c: 89 ee mov %ebp,%esi
3e: 81 .byte 0x81


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