[syzbot] [net?] possible deadlock in do_ipv6_setsockopt (4)

Hello,

syzbot found the following issue on:

HEAD commit: 2f5e6395714d Merge branch 'net-pse-pd-add-new-pse-c33-feat..
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=16f7e781980000
kernel config: https://syzkaller.appspot.com/x/.config?x=db697e01efa9d1d7
dashboard link: https://syzkaller.appspot.com/bug?extid=3433b5cb8b2b70933f8d
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/44296878e8d6/disk-2f5e6395.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a3f8523e4843/vmlinux-2f5e6395.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c40a60a2869f/bzImage-2f5e6395.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email protected]

======================================================
WARNING: possible circular locking dependency detected
6.10.0-rc6-syzkaller-01258-g2f5e6395714d #0 Not tainted
------------------------------------------------------
syz.4.1060/8537 is trying to acquire lock:
ffffffff8f5e7f48 (rtnl_mutex){+.+.}-{3:3}, at: do_ipv6_setsockopt+0x9e4/0x3630 net/ipv6/ipv6_sockglue.c:566

but task is already holding lock:
ffff88807b8c0a50 (&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_INET){+.+.}-{0:0}:
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
lock_sock_nested+0x48/0x100 net/core/sock.c:3543
do_ip_setsockopt+0x1a2d/0x3cd0 net/ipv4/ip_sockglue.c:1078
ip_setsockopt+0x63/0x100 net/ipv4/ip_sockglue.c:1417
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
do_ipv6_setsockopt+0x9e4/0x3630 net/ipv6/ipv6_sockglue.c:566
ipv6_setsockopt+0x5c/0x1a0 net/ipv6/ipv6_sockglue.c:993
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_INET --> &smc->clcsock_release_lock

Possible unsafe locking scenario:

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

*** DEADLOCK ***

1 lock held by syz.4.1060/8537:
#0: ffff88807b8c0a50 (&smc->clcsock_release_lock){+.+.}-{3:3}, at: smc_setsockopt+0x1c3/0xe50 net/smc/af_smc.c:3064

stack backtrace:
CPU: 1 PID: 8537 Comm: syz.4.1060 Not tainted 6.10.0-rc6-syzkaller-01258-g2f5e6395714d #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
do_ipv6_setsockopt+0x9e4/0x3630 net/ipv6/ipv6_sockglue.c:566
ipv6_setsockopt+0x5c/0x1a0 net/ipv6/ipv6_sockglue.c:993
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: 0033:0x7f0383b75bd9
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:00007f0384934048 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00007f0383d03f60 RCX: 00007f0383b75bd9
RDX: 0000000000000001 RSI: 0000000000000029 RDI: 0000000000000007
RBP: 00007f0383be4aa1 R08: 0000000000000004 R09: 0000000000000000
R10: 0000000020000080 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f0383d03f60 R15: 00007ffd8c5ba008
</TASK>


---
This report is generated by a bot. It may contain errors.
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syzbot engineers can be reached at [email protected].

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If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
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If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

syzbot has found a reproducer for the following issue on:

HEAD commit: c2933b2befe2 Merge tag 'net-6.14-rc1' of git://git.kernel...
git tree: net-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=12a22eb0580000
kernel config: https://syzkaller.appspot.com/x/.config?x=d033b14aeef39158
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12896d18580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12c69724580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c7667ae12603/disk-c2933b2b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/944ca63002c1/vmlinux-c2933b2b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/30748115bf0b/bzImage-c2933b2b.xz
6.13.0-syzkaller-09685-gc2933b2befe2 #0 Not tainted
------------------------------------------------------
syz-executor323/5834 is trying to acquire lock:
ffff8880352e2cd8 (sk_lock-AF_INET6){+.+.}-{0:0}, at: do_ipv6_setsockopt+0xbf7/0x3640 net/ipv6/ipv6_sockglue.c:567
ffffffff8fcbf088 (rtnl_mutex){+.+.}-{4:4}, at: do_ipv6_setsockopt+0x9e8/0x3640 net/ipv6/ipv6_sockglue.c:566
-> #1 (rtnl_mutex){+.+.}-{4:4}:
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
__mutex_lock_common kernel/locking/mutex.c:585 [inline]
__mutex_lock+0x19c/0x1010 kernel/locking/mutex.c:730
smc_vlan_by_tcpsk+0x399/0x4e0 net/smc/smc_core.c:1908
__smc_connect+0x296/0x1910 net/smc/af_smc.c:1520
smc_connect+0x868/0xde0 net/smc/af_smc.c:1696
__sys_connect_file net/socket.c:2040 [inline]
__sys_connect+0x288/0x2d0 net/socket.c:2059
__do_sys_connect net/socket.c:2065 [inline]
__se_sys_connect net/socket.c:2062 [inline]
__x64_sys_connect+0x7a/0x90 net/socket.c:2062
-> #0 (sk_lock-AF_INET6){+.+.}-{0:0}:
check_prev_add kernel/locking/lockdep.c:3163 [inline]
check_prevs_add kernel/locking/lockdep.c:3282 [inline]
validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3906
__lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5228
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
lock_sock_nested+0x48/0x100 net/core/sock.c:3645
do_ipv6_setsockopt+0xbf7/0x3640 net/ipv6/ipv6_sockglue.c:567
ipv6_setsockopt+0x5d/0x170 net/ipv6/ipv6_sockglue.c:993
do_sock_setsockopt+0x3af/0x720 net/socket.c:2298
__sys_setsockopt net/socket.c:2323 [inline]
__do_sys_setsockopt net/socket.c:2329 [inline]
__se_sys_setsockopt net/socket.c:2326 [inline]
__x64_sys_setsockopt+0x1ee/0x280 net/socket.c:2326
lock(rtnl_mutex);
lock(sk_lock-AF_INET6);
lock(rtnl_mutex);
lock(sk_lock-AF_INET6);

*** DEADLOCK ***

1 lock held by syz-executor323/5834:
#0: ffffffff8fcbf088 (rtnl_mutex){+.+.}-{4:4}, at: do_ipv6_setsockopt+0x9e8/0x3640 net/ipv6/ipv6_sockglue.c:566

stack backtrace:
CPU: 0 UID: 0 PID: 5834 Comm: syz-executor323 Not tainted 6.13.0-syzkaller-09685-gc2933b2befe2 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
print_circular_bug+0x13a/0x1b0 kernel/locking/lockdep.c:2076
check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2208
check_prev_add kernel/locking/lockdep.c:3163 [inline]
check_prevs_add kernel/locking/lockdep.c:3282 [inline]
validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3906
__lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5228
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
lock_sock_nested+0x48/0x100 net/core/sock.c:3645
do_ipv6_setsockopt+0xbf7/0x3640 net/ipv6/ipv6_sockglue.c:567
ipv6_setsockopt+0x5d/0x170 net/ipv6/ipv6_sockglue.c:993
do_sock_setsockopt+0x3af/0x720 net/socket.c:2298
__sys_setsockopt net/socket.c:2323 [inline]
__do_sys_setsockopt net/socket.c:2329 [inline]
__se_sys_setsockopt net/socket.c:2326 [inline]
__x64_sys_setsockopt+0x1ee/0x280 net/socket.c:2326
RIP: 0033:0x7f5f02247369
Code: 48 83 c4 28 c3 e8 37 17 00 00 0f 1f 80 00 00 00 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe9a248bd8 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00007ffe9a248da8 RCX: 00007f5f02247369
RDX: 000000000000001b RSI: 0000000000000029 RDI: 0000000000000004
RBP: 00007f5f022ba610 R08: 0000000000000000 R09: 00007ffe9a248da8
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffe9a248d98


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

On Sun, 02 Feb 2025 14:01:18 -0800
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12c69724580000

#syz test

--- x/net/smc/af_smc.c
+++ y/net/smc/af_smc.c
@@ -1597,6 +1597,7 @@ static void smc_connect_work(struct work
rc = 0;
}
release_sock(smc->clcsock->sk);
+ rtnl_lock();
lock_sock(&smc->sk);
if (rc != 0 || smc->sk.sk_err) {
smc->sk.sk_state = SMC_CLOSED;
@@ -1624,6 +1625,7 @@ out:
}
}
release_sock(&smc->sk);
+ rtnl_unlock();
}

int smc_connect(struct socket *sock, struct sockaddr *addr,
@@ -1641,6 +1643,7 @@ int smc_connect(struct socket *sock, str
if (addr->sa_family != AF_INET && addr->sa_family != AF_INET6)
goto out_err;

+ rtnl_lock();
lock_sock(sk);
switch (sock->state) {
default:
@@ -1703,6 +1706,7 @@ connected:
sock->state = SS_CONNECTED;
out:
release_sock(sk);
+ rtnl_unlock();
out_err:
return rc;
}
--- x/net/smc/smc_core.c
+++ y/net/smc/smc_core.c
@@ -1888,6 +1888,7 @@ int smc_vlan_by_tcpsk(struct socket *clc
struct net_device *ndev;
int rc = 0;

+ ASSERT_RTNL();
ini->vlan_id = 0;
if (!dst) {
rc = -ENOTCONN;
@@ -1905,9 +1906,7 @@ int smc_vlan_by_tcpsk(struct socket *clc
}

priv.data = (void *)&ini->vlan_id;
- rtnl_lock();
netdev_walk_all_lower_dev(ndev, smc_vlan_by_tcpsk_walk, &priv);
- rtnl_unlock();

out_rel:
dst_release(dst);
--

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
possible deadlock in smc_pnet_find_ism_resource

============================================
WARNING: possible recursive locking detected
6.13.0-syzkaller-09685-gc2933b2befe2-dirty #0 Not tainted
--------------------------------------------
syz.0.16/6653 is trying to acquire lock:
ffffffff8fcbf088 (rtnl_mutex){+.+.}-{4:4}, at: pnet_find_base_ndev net/smc/smc_pnet.c:945 [inline]
ffffffff8fcbf088 (rtnl_mutex){+.+.}-{4:4}, at: smc_pnet_find_ism_by_pnetid net/smc/smc_pnet.c:1101 [inline]
ffffffff8fcbf088 (rtnl_mutex){+.+.}-{4:4}, at: smc_pnet_find_ism_resource+0xe1/0x510 net/smc/smc_pnet.c:1152
ffffffff8fcbf088 (rtnl_mutex){+.+.}-{4:4}, at: smc_connect+0xb2/0xde0 net/smc/af_smc.c:1646
----
lock(rtnl_mutex);
lock(rtnl_mutex);

*** DEADLOCK ***

May be due to missing lock nesting notation

2 locks held by syz.0.16/6653:
#0: ffffffff8fcbf088 (rtnl_mutex){+.+.}-{4:4}, at: smc_connect+0xb2/0xde0 net/smc/af_smc.c:1646
#1: ffff88806d868258 (sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1624 [inline]
#1: ffff88806d868258 (sk_lock-AF_INET6){+.+.}-{0:0}, at: smc_connect+0xbc/0xde0 net/smc/af_smc.c:1647

stack backtrace:
CPU: 0 UID: 0 PID: 6653 Comm: syz.0.16 Not tainted 6.13.0-syzkaller-09685-gc2933b2befe2-dirty #0
print_deadlock_bug+0x483/0x620 kernel/locking/lockdep.c:3039
check_deadlock kernel/locking/lockdep.c:3091 [inline]
validate_chain+0x15e2/0x5920 kernel/locking/lockdep.c:3893
pnet_find_base_ndev net/smc/smc_pnet.c:945 [inline]
smc_pnet_find_ism_by_pnetid net/smc/smc_pnet.c:1101 [inline]
smc_pnet_find_ism_resource+0xe1/0x510 net/smc/smc_pnet.c:1152
smc_find_ism_device net/smc/af_smc.c:1011 [inline]
smc_find_proposal_devices net/smc/af_smc.c:1096 [inline]
__smc_connect+0x391/0x1910 net/smc/af_smc.c:1526
smc_connect+0x872/0xde0 net/smc/af_smc.c:1699
RIP: 0033:0x7fbdb618cda9
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:00007fbdb7056038 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 00007fbdb63a5fa0 RCX: 00007fbdb618cda9
RDX: 000000000000001c RSI: 0000000020000000 RDI: 0000000000000003
RBP: 00007fbdb620e2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fbdb63a5fa0 R15: 00007fff45686908
</TASK>


Tested on:

commit: c2933b2b Merge tag 'net-6.14-rc1' of git://git.kernel...
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=17c65724580000
patch: https://syzkaller.appspot.com/x/patch.diff?x=13691764580000