possible deadlock in ipv6_sock_mc_close (3)

Status: auto-obsoleted due to no activity on 2025/04/12 07:57
Subsystems: net
[Documentation on labels]
Reported-by: syzbot+9fb9097b40bf7ca5172c@syzkaller.appspotmail.com
First crash: 570d, last: 570d
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [net?] possible deadlock in ipv6_sock_mc_close (3) 0 (1) 2025/01/06 08:05
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream possible deadlock in ipv6_sock_mc_close (2) net 4 1 693d 691d 0/29 auto-obsoleted due to no activity on 2024/12/10 03:31
upstream possible deadlock in ipv6_sock_mc_close net 4 C done unreliable 6 1935d 1973d 0/29 closed as invalid on 2023/08/03 10:00
upstream possible deadlock in ipv6_sock_mc_close (4) net 4 C done 7 232d 230d 29/29 fixed on 2026/01/21 09:45

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
6.13.0-rc5-syzkaller-00006-g56e6a3499e14 #0 Not tainted
------------------------------------------------------
syz.2.174/6655 is trying to acquire lock:
ffffffff8fedc988 (rtnl_mutex){+.+.}-{4:4}, at: ipv6_sock_mc_close+0xdb/0x120 net/ipv6/mcast.c:354

but task is already holding lock:
ffff888051730aa8 (&smc->clcsock_release_lock){+.+.}-{4:4}, at: smc_clcsock_release+0x75/0xe0 net/smc/smc_close.c:30

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&smc->clcsock_release_lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:585 [inline]
       __mutex_lock+0x19b/0xa60 kernel/locking/mutex.c:735
       smc_switch_to_fallback+0x2d/0xa00 net/smc/af_smc.c:903
       smc_sendmsg+0x13d/0x520 net/smc/af_smc.c:2778
       sock_sendmsg_nosec net/socket.c:711 [inline]
       __sock_sendmsg net/socket.c:726 [inline]
       ____sys_sendmsg+0xaaf/0xc90 net/socket.c:2583
       ___sys_sendmsg+0x135/0x1e0 net/socket.c:2637
       __sys_sendmsg+0x16e/0x220 net/socket.c:2669
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (sk_lock-AF_INET6){+.+.}-{0:0}:
       lock_sock_nested+0x3a/0xf0 net/core/sock.c:3622
       lock_sock include/net/sock.h:1623 [inline]
       sockopt_lock_sock net/core/sock.c:1126 [inline]
       sockopt_lock_sock+0x54/0x70 net/core/sock.c:1117
       do_ipv6_setsockopt+0x2160/0x4520 net/ipv6/ipv6_sockglue.c:567
       ipv6_setsockopt+0xcb/0x170 net/ipv6/ipv6_sockglue.c:993
       rawv6_setsockopt+0xd7/0x680 net/ipv6/raw.c:1054
       do_sock_setsockopt+0x222/0x480 net/socket.c:2313
       __sys_setsockopt+0x1a0/0x230 net/socket.c:2338
       __do_sys_setsockopt net/socket.c:2344 [inline]
       __se_sys_setsockopt net/socket.c:2341 [inline]
       __x64_sys_setsockopt+0xbd/0x160 net/socket.c:2341
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (rtnl_mutex){+.+.}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3161 [inline]
       check_prevs_add kernel/locking/lockdep.c:3280 [inline]
       validate_chain kernel/locking/lockdep.c:3904 [inline]
       __lock_acquire+0x249e/0x3c40 kernel/locking/lockdep.c:5226
       lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5849
       __mutex_lock_common kernel/locking/mutex.c:585 [inline]
       __mutex_lock+0x19b/0xa60 kernel/locking/mutex.c:735
       ipv6_sock_mc_close+0xdb/0x120 net/ipv6/mcast.c:354
       inet6_release+0x3f/0x70 net/ipv6/af_inet6.c:482
       __sock_release net/socket.c:640 [inline]
       sock_release+0x8e/0x1d0 net/socket.c:668
       smc_clcsock_release+0xb7/0xe0 net/smc/smc_close.c:34
       __smc_release+0x5c2/0x880 net/smc/af_smc.c:301
       smc_release+0x1fc/0x5f0 net/smc/af_smc.c:344
       __sock_release+0xb0/0x270 net/socket.c:640
       sock_close+0x1c/0x30 net/socket.c:1408
       __fput+0x3f8/0xb60 fs/file_table.c:450
       task_work_run+0x14e/0x250 kernel/task_work.c:239
       resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
       exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
       exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
       __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
       syscall_exit_to_user_mode+0x27b/0x2a0 kernel/entry/common.c:218
       do_syscall_64+0xda/0x250 arch/x86/entry/common.c:89
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
  rtnl_mutex --> sk_lock-AF_INET6 --> 
&smc->clcsock_release_lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&smc->clcsock_release_lock);
                               lock(sk_lock-AF_INET6);
                               lock(&smc->clcsock_release_lock);
  lock(rtnl_mutex);

 *** DEADLOCK ***

2 locks held by syz.2.174/6655:
 #0: ffff88804b71be08 (&sb->s_type->i_mutex_key#10){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:818 [inline]
 #0: ffff88804b71be08 (&sb->s_type->i_mutex_key#10){+.+.}-{4:4}, at: __sock_release+0x86/0x270 net/socket.c:639
 #1: ffff888051730aa8 (&smc->clcsock_release_lock){+.+.}-{4:4}, at: smc_clcsock_release+0x75/0xe0 net/smc/smc_close.c:30

stack backtrace:
CPU: 3 UID: 0 PID: 6655 Comm: syz.2.174 Not tainted 6.13.0-rc5-syzkaller-00006-g56e6a3499e14 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_circular_bug+0x419/0x5d0 kernel/locking/lockdep.c:2074
 check_noncircular+0x31a/0x400 kernel/locking/lockdep.c:2206
 check_prev_add kernel/locking/lockdep.c:3161 [inline]
 check_prevs_add kernel/locking/lockdep.c:3280 [inline]
 validate_chain kernel/locking/lockdep.c:3904 [inline]
 __lock_acquire+0x249e/0x3c40 kernel/locking/lockdep.c:5226
 lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5849
 __mutex_lock_common kernel/locking/mutex.c:585 [inline]
 __mutex_lock+0x19b/0xa60 kernel/locking/mutex.c:735
 ipv6_sock_mc_close+0xdb/0x120 net/ipv6/mcast.c:354
 inet6_release+0x3f/0x70 net/ipv6/af_inet6.c:482
 __sock_release net/socket.c:640 [inline]
 sock_release+0x8e/0x1d0 net/socket.c:668
 smc_clcsock_release+0xb7/0xe0 net/smc/smc_close.c:34
 __smc_release+0x5c2/0x880 net/smc/af_smc.c:301
 smc_release+0x1fc/0x5f0 net/smc/af_smc.c:344
 __sock_release+0xb0/0x270 net/socket.c:640
 sock_close+0x1c/0x30 net/socket.c:1408
 __fput+0x3f8/0xb60 fs/file_table.c:450
 task_work_run+0x14e/0x250 kernel/task_work.c:239
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x27b/0x2a0 kernel/entry/common.c:218
 do_syscall_64+0xda/0x250 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe2ec385d29
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:00007ffc27879538 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 000000000000e61f RCX: 00007fe2ec385d29
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007fe2ec577ba0 R08: 0000000000000001 R09: 00007ffc2787982f
R10: 00007fe2ec200000 R11: 0000000000000246 R12: 000000000000e688
R13: 00007fe2ec575fa0 R14: 0000000000000032 R15: ffffffffffffffff
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/01/02 07:56 upstream 56e6a3499e14 d3ccff63 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream possible deadlock in ipv6_sock_mc_close
* Struck through repros no longer work on HEAD.