syzbot


WARNING: refcount bug in ax25_setsockopt

Status: upstream: reported C repro on 2025/07/11 15:28
Subsystems: hams
[Documentation on labels]
Reported-by: syzbot+0ee4da32f91ae2a3f015@syzkaller.appspotmail.com
First crash: 140d, last: 10d
Cause bisection: failed (error log, bisect log)
  
Fix bisection: failed (error log, bisect log)
  
Discussions (2)
Title Replies (including bot) Last reply
[syzbot] Monthly hams report (Aug 2025) 0 (1) 2025/08/25 08:40
[syzbot] [hams?] WARNING: refcount bug in ax25_setsockopt 1 (3) 2025/07/12 01:44
Last patch testing requests (5)
Created Duration User Patch Repo Result
2025/08/10 23:18 29m retest repro net-next report log
2025/07/12 00:58 45m hdanton@sina.com patch net-next OK log
2025/07/05 16:03 21m retest repro net-next report log
2025/04/26 15:09 1h04m retest repro net-next report log
2025/04/26 15:09 40m retest repro net-next report log

Sample crash report:
------------[ cut here ]------------
refcount_t: addition on 0; use-after-free.
WARNING: CPU: 1 PID: 6618 at lib/refcount.c:25 refcount_warn_saturate+0xfa/0x1d0 lib/refcount.c:25
Modules linked in:
CPU: 1 UID: 0 PID: 6618 Comm: syz.1.492 Not tainted 6.16.0-rc7-syzkaller-00100-gafd8c2c9e2e2 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:refcount_warn_saturate+0xfa/0x1d0 lib/refcount.c:25
Code: 00 00 e8 e9 c2 ff fc 5b 41 5e c3 cc cc cc cc cc e8 db c2 ff fc c6 05 2d 6a cb 0a 01 90 48 c7 c7 c0 42 e2 8b e8 37 b2 c3 fc 90 <0f> 0b 90 90 eb d7 e8 bb c2 ff fc c6 05 0e 6a cb 0a 01 90 48 c7 c7
RSP: 0018:ffffc9000d097d48 EFLAGS: 00010246
RAX: a70fbede0ffcdb00 RBX: 0000000000000002 RCX: ffff88801eb1da00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000002
RBP: ffffc9000d097e48 R08: ffff8880b8724293 R09: 1ffff110170e4852
R10: dffffc0000000000 R11: ffffed10170e4853 R12: 1ffff11006b15f05
R13: 1ffff92001a12fb4 R14: ffff8880355296c8 R15: dffffc0000000000
FS:  00005555931e2500(0000) GS:ffff888125d23000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa4413802d8 CR3: 0000000075992000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 ax25_setsockopt+0xabb/0xc20 net/ax25/af_ax25.c:705
 do_sock_setsockopt+0x17c/0x1b0 net/socket.c:2296
 __sys_setsockopt net/socket.c:2321 [inline]
 __do_sys_setsockopt net/socket.c:2327 [inline]
 __se_sys_setsockopt net/socket.c:2324 [inline]
 __x64_sys_setsockopt+0x13f/0x1b0 net/socket.c:2324
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f321f98e9a9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe0aab2ec8 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00007f321fbb5fa0 RCX: 00007f321f98e9a9
RDX: 0000000000000019 RSI: 0000000000000101 RDI: 000000000000000c
RBP: 00007f321fa10d69 R08: 0000000000000010 R09: 0000000000000000
R10: 00002000000001c0 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f321fbb5fa0 R14: 00007f321fbb5fa0 R15: 0000000000000005
 </TASK>

Crashes (7):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/27 22:59 net afd8c2c9e2e2 fb8f743d .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING: refcount bug in ax25_setsockopt
2025/04/12 14:08 net-next faeefc173be4 0bd6db41 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING: refcount bug in ax25_setsockopt
2025/04/12 11:59 net-next faeefc173be4 0bd6db41 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING: refcount bug in ax25_setsockopt
2025/08/20 18:58 net-next 5c69e0b395c1 bd178e57 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING: refcount bug in ax25_setsockopt
2025/07/20 09:43 net-next 4701ee5044fb 7117feec .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING: refcount bug in ax25_setsockopt
2025/06/09 22:44 net-next 2c7e4a2663a1 4826c28e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING: refcount bug in ax25_setsockopt
2025/04/12 03:42 net-next faeefc173be4 12ba9c21 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING: refcount bug in ax25_setsockopt
* Struck through repros no longer work on HEAD.