[syzbot] [net?] [s390?] possible deadlock in smc_vlan_by_tcpsk

Hello,

syzbot found the following issue on:

HEAD commit: 185d72112b95 net: xilinx: axienet: Enable multicast by def..
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=13e0ec8e980000
kernel config: https://syzkaller.appspot.com/x/.config?x=e78fc116033e0ab7
dashboard link: https://syzkaller.appspot.com/bug?extid=c75d1de73d3b8b76272f
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/e84f50e44254/disk-185d7211.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/df64b575cc01/vmlinux-185d7211.xz
kernel image: https://storage.googleapis.com/syzbot-assets/16ad5d1d433b/bzImage-185d7211.xz

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

syz-executor.2[7759] is installing a program with bpf_probe_write_user helper that may corrupt user memory!
syz-executor.2[7759] is installing a program with bpf_probe_write_user helper that may corrupt user memory!
======================================================
WARNING: possible circular locking dependency detected
6.10.0-rc4-syzkaller-00869-g185d72112b95 #0 Not tainted
------------------------------------------------------
syz-executor.2/7759 is trying to acquire lock:
ffffffff8f5e6f48 (rtnl_mutex){+.+.}-{3:3}, at: smc_vlan_by_tcpsk+0x399/0x4e0 net/smc/smc_core.c:1853

but task is already holding lock:
ffff88801bed0258 (sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1602 [inline]
ffff88801bed0258 (sk_lock-AF_INET6){+.+.}-{0:0}, at: smc_connect+0xb7/0xde0 net/smc/af_smc.c:1650

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #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
smc_vlan_by_tcpsk+0x399/0x4e0 net/smc/smc_core.c:1853
__smc_connect+0x2a4/0x1890 net/smc/af_smc.c:1522
smc_connect+0x868/0xde0 net/smc/af_smc.c:1702
__sys_connect_file net/socket.c:2049 [inline]
__sys_connect+0x2df/0x310 net/socket.c:2066
__do_sys_connect net/socket.c:2076 [inline]
__se_sys_connect net/socket.c:2073 [inline]
__x64_sys_connect+0x7a/0x90 net/socket.c:2073
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:

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(sk_lock-AF_INET6);
lock(rtnl_mutex);
lock(sk_lock-AF_INET6);
lock(rtnl_mutex);

*** DEADLOCK ***

1 lock held by syz-executor.2/7759:
#0: ffff88801bed0258 (sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1602 [inline]
#0: ffff88801bed0258 (sk_lock-AF_INET6){+.+.}-{0:0}, at: smc_connect+0xb7/0xde0 net/smc/af_smc.c:1650

stack backtrace:
CPU: 1 PID: 7759 Comm: syz-executor.2 Not tainted 6.10.0-rc4-syzkaller-00869-g185d72112b95 #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
smc_vlan_by_tcpsk+0x399/0x4e0 net/smc/smc_core.c:1853
__smc_connect+0x2a4/0x1890 net/smc/af_smc.c:1522
smc_connect+0x868/0xde0 net/smc/af_smc.c:1702
__sys_connect_file net/socket.c:2049 [inline]
__sys_connect+0x2df/0x310 net/socket.c:2066
__do_sys_connect net/socket.c:2076 [inline]
__se_sys_connect net/socket.c:2073 [inline]
__x64_sys_connect+0x7a/0x90 net/socket.c:2073
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: 0033:0x7f0b3687d0a9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f0b3764b0c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 00007f0b369b3f80 RCX: 00007f0b3687d0a9
RDX: 000000000000001c RSI: 00000000200000c0 RDI: 000000000000000a
RBP: 00007f0b368ec074 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f0b369b3f80 R15: 00007fff165a7738
</TASK>


---
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syzbot has found a reproducer for the following issue on:

HEAD commit: d4560686726f Merge tag 'for_linus' of git://git.kernel.org..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=119f30f5980000
kernel config: https://syzkaller.appspot.com/x/.config?x=505ed4a1dd93463a
dashboard link: https://syzkaller.appspot.com/bug?extid=c75d1de73d3b8b76272f
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17e2fc5d980000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16307a7d980000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7bc7510fe41f/non_bootable_disk-d4560686.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3304e311b45d/vmlinux-d4560686.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c5fa8d141fd4/bzImage-d4560686.xz
6.11.0-rc2-syzkaller-00013-gd4560686726f #0 Not tainted
------------------------------------------------------
syz-executor492/5336 is trying to acquire lock:
ffffffff8fa20ee8 (rtnl_mutex){+.+.}-{3:3}, at: smc_vlan_by_tcpsk+0x251/0x620 net/smc/smc_core.c:1853
ffff888033d60258 (sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1607 [inline]
ffff888033d60258 (sk_lock-AF_INET6){+.+.}-{0:0}, at: smc_connect+0xd5/0x760 net/smc/af_smc.c:1650
lock_sock_nested+0x3a/0xf0 net/core/sock.c:3543
lock_sock include/net/sock.h:1607 [inline]
sockopt_lock_sock net/core/sock.c:1061 [inline]
sockopt_lock_sock+0x54/0x70 net/core/sock.c:1052
do_ipv6_setsockopt+0x216a/0x47b0 net/ipv6/ipv6_sockglue.c:567
ipv6_setsockopt+0xe3/0x1a0 net/ipv6/ipv6_sockglue.c:993
udpv6_setsockopt+0x7d/0xd0 net/ipv6/udp.c:1702
do_sock_setsockopt+0x222/0x480 net/socket.c:2324
__sys_setsockopt+0x1a4/0x270 net/socket.c:2347
__do_sys_setsockopt net/socket.c:2356 [inline]
__se_sys_setsockopt net/socket.c:2353 [inline]
__x64_sys_setsockopt+0xbd/0x160 net/socket.c:2353
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
check_prev_add kernel/locking/lockdep.c:3133 [inline]
check_prevs_add kernel/locking/lockdep.c:3252 [inline]
validate_chain kernel/locking/lockdep.c:3868 [inline]
__lock_acquire+0x24ed/0x3cb0 kernel/locking/lockdep.c:5142
lock_acquire kernel/locking/lockdep.c:5759 [inline]
lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5724
__mutex_lock_common kernel/locking/mutex.c:608 [inline]
__mutex_lock+0x175/0x9c0 kernel/locking/mutex.c:752
smc_vlan_by_tcpsk+0x251/0x620 net/smc/smc_core.c:1853
__smc_connect+0x44d/0x4830 net/smc/af_smc.c:1522
smc_connect+0x2fc/0x760 net/smc/af_smc.c:1702
__sys_connect_file+0x15f/0x1a0 net/socket.c:2061
__sys_connect+0x149/0x170 net/socket.c:2078
__do_sys_connect net/socket.c:2088 [inline]
__se_sys_connect net/socket.c:2085 [inline]
__x64_sys_connect+0x72/0xb0 net/socket.c:2085
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
1 lock held by syz-executor492/5336:
#0: ffff888033d60258 (sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1607 [inline]
#0: ffff888033d60258 (sk_lock-AF_INET6){+.+.}-{0:0}, at: smc_connect+0xd5/0x760 net/smc/af_smc.c:1650

stack backtrace:
CPU: 1 UID: 0 PID: 5336 Comm: syz-executor492 Not tainted 6.11.0-rc2-syzkaller-00013-gd4560686726f #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:93 [inline]
dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:119
check_noncircular+0x31a/0x400 kernel/locking/lockdep.c:2186
check_prev_add kernel/locking/lockdep.c:3133 [inline]
check_prevs_add kernel/locking/lockdep.c:3252 [inline]
validate_chain kernel/locking/lockdep.c:3868 [inline]
__lock_acquire+0x24ed/0x3cb0 kernel/locking/lockdep.c:5142
lock_acquire kernel/locking/lockdep.c:5759 [inline]
lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5724
__mutex_lock_common kernel/locking/mutex.c:608 [inline]
__mutex_lock+0x175/0x9c0 kernel/locking/mutex.c:752
smc_vlan_by_tcpsk+0x251/0x620 net/smc/smc_core.c:1853
__smc_connect+0x44d/0x4830 net/smc/af_smc.c:1522
smc_connect+0x2fc/0x760 net/smc/af_smc.c:1702
__sys_connect_file+0x15f/0x1a0 net/socket.c:2061
__sys_connect+0x149/0x170 net/socket.c:2078
__do_sys_connect net/socket.c:2088 [inline]
__se_sys_connect net/socket.c:2085 [inline]
__x64_sys_connect+0x72/0xb0 net/socket.c:2085
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
RIP: 0033:0x7f6fc285ad49
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 01 1a 00 00 90 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:00007ffeaafd57c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f6fc285ad49
RDX: 000000000000001c RSI: 0000000020000200 RDI: 0000000000000004
RBP: 00000000000f4240 R08: 0000000000000001 R09: 0000000000000001
R10: 0000000000000001 R11: 0000000000000246 R12: 00007ffeaafd5820
R13: 00007f6fc28a8406 R14: 0000000000000003 R15: 00007ffeaafd5800
</TASK>


---
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***

Subject: Re: [syzbot] [net?] [s390?] possible deadlock in smc_vlan_by_tcpsk
Author: [email protected]



#syz test

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: [email protected]
Tested-by: [email protected]

Tested on:

commit: 77f58789 Merge tag 'arm-fixes-6.11-3' of git://git.ker..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10915807980000
kernel config: https://syzkaller.appspot.com/x/.config?x=cf6caa9e11507c7f
patch: https://syzkaller.appspot.com/x/patch.diff?x=12c4a0a9980000

Note: testing is done by a robot and is best-effort only.