syzbot


WARNING: refcount bug in blk_done_softirq (2)

Status: upstream: reported syz repro on 2024/12/20 13:24
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+cb362dc128596773bb9d@syzkaller.appspotmail.com
First crash: 96d, last: 21d
Bug presence (2)
Date Name Commit Repro Result
2025/03/25 linux-5.15.y (ToT) 0c935c049b5c C [report] WARNING: refcount bug in blk_mq_dispatch_rq_list
2025/03/25 upstream (ToT) 327ecdbc0fda C Didn't crash
Similar bugs (1)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 WARNING: refcount bug in blk_done_softirq 1 612d 612d 0/3 auto-obsoleted due to no activity on 2023/11/01 11:50
Last patch testing requests (1)
Created Duration User Patch Repo Result
2025/03/20 23:37 11m retest repro linux-5.15.y report log

Sample crash report:
------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 0 PID: 14 at lib/refcount.c:28 refcount_warn_saturate+0x14e/0x1a0 lib/refcount.c:28
Modules linked in:
CPU: 0 PID: 14 Comm: ksoftirqd/0 Not tainted 5.15.178-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:refcount_warn_saturate+0x14e/0x1a0 lib/refcount.c:28
Code: 09 01 48 c7 c7 c0 b5 f9 8a e8 2e 42 38 fd 0f 0b eb 8d e8 85 a8 6c fd c6 05 cb 10 e3 09 01 48 c7 c7 20 b6 f9 8a e8 12 42 38 fd <0f> 0b e9 6e ff ff ff e8 66 a8 6c fd c6 05 ad 10 e3 09 01 48 c7 c7
RSP: 0018:ffffc90000d37c80 EFLAGS: 00010246
RAX: 19acb288cbd26200 RBX: 0000000000000003 RCX: ffff88813ff21dc0
RDX: 0000000000000100 RSI: 0000000000000100 RDI: 0000000000000000
RBP: 0000000000000003 R08: ffffffff8166aa8c R09: fffff520001a6ed1
R10: 0000000000000000 R11: dffffc0000000001 R12: 0000000000000004
R13: ffffffff8c80a0e0 R14: 0000000000000000 R15: ffff888020e70200
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000400000000280 CR3: 000000007958b000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 blk_complete_reqs block/blk-mq.c:587 [inline]
 blk_done_softirq+0xf2/0x130 block/blk-mq.c:592
 handle_softirqs+0x3a7/0x930 kernel/softirq.c:558
 run_ksoftirqd+0xc6/0x120 kernel/softirq.c:925
 smpboot_thread_fn+0x51b/0x9d0 kernel/smpboot.c:164
 kthread+0x3f6/0x4f0 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/03/05 06:58 linux-5.15.y c16c81c81336 c3901742 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: refcount bug in blk_done_softirq
2025/03/06 06:20 linux-5.15.y c16c81c81336 831e3629 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: refcount bug in blk_done_softirq
2024/12/20 13:24 linux-5.15.y 91786f140358 0f61b415 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: refcount bug in blk_done_softirq
* Struck through repros no longer work on HEAD.