syzbot


possible deadlock in ip_mroute_setsockopt

Status: upstream: reported on 2024/07/10 15:21
Subsystems: net
[Documentation on labels]
Reported-by: syzbot+e227429f6fa77945d7e4@syzkaller.appspotmail.com
First crash: 3d04h, last: 3d04h
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [net?] possible deadlock in ip_mroute_setsockopt 0 (1) 2024/07/10 15:21

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
6.10.0-rc6-syzkaller-01403-g40ab9e0dc865 #0 Not tainted
------------------------------------------------------
syz.1.1201/8409 is trying to acquire lock:
ffffffff8f5e9108 (rtnl_mutex){+.+.}-{3:3}, at: ip_mroute_setsockopt+0x15b/0x1190 net/ipv4/ipmr.c:1369

but task is already holding lock:
ffff88805f784c50 (&smc->clcsock_release_lock){+.+.}-{3:3}, at: smc_setsockopt+0x1c3/0xe50 net/smc/af_smc.c:3064

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&smc->clcsock_release_lock){+.+.}-{3:3}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
       __mutex_lock_common kernel/locking/mutex.c:608 [inline]
       __mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752
       smc_switch_to_fallback+0x35/0xd00 net/smc/af_smc.c:902
       smc_sendmsg+0x11f/0x530 net/smc/af_smc.c:2779
       sock_sendmsg_nosec net/socket.c:730 [inline]
       __sock_sendmsg+0x221/0x270 net/socket.c:745
       __sys_sendto+0x3a4/0x4f0 net/socket.c:2192
       __do_sys_sendto net/socket.c:2204 [inline]
       __se_sys_sendto net/socket.c:2200 [inline]
       __x64_sys_sendto+0xde/0x100 net/socket.c:2200
       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

-> #1 (sk_lock-AF_INET6){+.+.}-{0:0}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
       lock_sock_nested+0x48/0x100 net/core/sock.c:3543
       do_ipv6_setsockopt+0xbf3/0x3630 net/ipv6/ipv6_sockglue.c:567
       ipv6_setsockopt+0x5c/0x1a0 net/ipv6/ipv6_sockglue.c:993
       do_sock_setsockopt+0x3af/0x720 net/socket.c:2312
       __sys_setsockopt+0x1ae/0x250 net/socket.c:2335
       __do_sys_setsockopt net/socket.c:2344 [inline]
       __se_sys_setsockopt net/socket.c:2341 [inline]
       __x64_sys_setsockopt+0xb5/0xd0 net/socket.c:2341
       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

-> #0 (rtnl_mutex){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain+0x18e0/0x5900 kernel/locking/lockdep.c:3869
       __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
       __mutex_lock_common kernel/locking/mutex.c:608 [inline]
       __mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752
       ip_mroute_setsockopt+0x15b/0x1190 net/ipv4/ipmr.c:1369
       do_ip_setsockopt+0x129f/0x3cd0 net/ipv4/ip_sockglue.c:948
       ip_setsockopt+0x63/0x100 net/ipv4/ip_sockglue.c:1417
       smc_setsockopt+0x275/0xe50 net/smc/af_smc.c:3072
       do_sock_setsockopt+0x3af/0x720 net/socket.c:2312
       __sys_setsockopt+0x1ae/0x250 net/socket.c:2335
       __do_sys_setsockopt net/socket.c:2344 [inline]
       __se_sys_setsockopt net/socket.c:2341 [inline]
       __x64_sys_setsockopt+0xb5/0xd0 net/socket.c:2341
       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

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 ***

1 lock held by syz.1.1201/8409:
 #0: ffff88805f784c50 (&smc->clcsock_release_lock){+.+.}-{3:3}, at: smc_setsockopt+0x1c3/0xe50 net/smc/af_smc.c:3064

stack backtrace:
CPU: 0 PID: 8409 Comm: syz.1.1201 Not tainted 6.10.0-rc6-syzkaller-01403-g40ab9e0dc865 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain+0x18e0/0x5900 kernel/locking/lockdep.c:3869
 __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
 __mutex_lock_common kernel/locking/mutex.c:608 [inline]
 __mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752
 ip_mroute_setsockopt+0x15b/0x1190 net/ipv4/ipmr.c:1369
 do_ip_setsockopt+0x129f/0x3cd0 net/ipv4/ip_sockglue.c:948
 ip_setsockopt+0x63/0x100 net/ipv4/ip_sockglue.c:1417
 smc_setsockopt+0x275/0xe50 net/smc/af_smc.c:3072
 do_sock_setsockopt+0x3af/0x720 net/socket.c:2312
 __sys_setsockopt+0x1ae/0x250 net/socket.c:2335
 __do_sys_setsockopt net/socket.c:2344 [inline]
 __se_sys_setsockopt net/socket.c:2341 [inline]
 __x64_sys_setsockopt+0xb5/0xd0 net/socket.c:2341
 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: 0033:0x7f5dfd375bd9
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:00007f5dfe06b048 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00007f5dfd503f60 RCX: 00007f5dfd375bd9
RDX: 00000000000000ca RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00007f5dfd3e4e60 R08: 0000000000000010 R09: 0000000000000000
R10: 0000000020000100 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f5dfd503f60 R15: 00007fff4a8a5b18
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/07/10 06:40 net-next 40ab9e0dc865 79d68ada .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in ip_mroute_setsockopt
* Struck through repros no longer work on HEAD.