linux-kernel - Re: [syzbot] [net?] possible deadlock in do_ip

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Message-ID: <000000000000c9d5c4062070a857@google.com>
Date: Sat, 24 Aug 2024 09:48:20 -0700
From: syzbot <syzbot+e4c27043b9315839452d@...kaller.appspotmail.com>
To: davem@...emloft.net, dsahern@...nel.org, edumazet@...gle.com, 
	kuba@...nel.org, linux-kernel@...r.kernel.org, netdev@...r.kernel.org, 
	pabeni@...hat.com, syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [net?] possible deadlock in do_ip_setsockopt (4)

syzbot has found a reproducer for the following issue on:

HEAD commit:    d2bafcf224f3 Merge tag 'cgroup-for-6.11-rc4-fixes' of git:..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=1214fd05980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=4fc2afd52fd008bb
dashboard link: https://syzkaller.appspot.com/bug?extid=e4c27043b9315839452d
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=10e70233980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10a44815980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/8864ed10d80d/disk-d2bafcf2.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6165bc385834/vmlinux-d2bafcf2.xz
kernel image: https://storage.googleapis.com/syzbot-assets/83bf9db2da50/bzImage-d2bafcf2.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e4c27043b9315839452d@...kaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.11.0-rc4-syzkaller-00255-gd2bafcf224f3 #0 Not tainted
------------------------------------------------------
syz-executor266/5220 is trying to acquire lock:
ffff888017752958 (sk_lock-AF_INET){+.+.}-{0:0}, at: do_ip_setsockopt+0x1a2d/0x3cd0 net/ipv4/ip_sockglue.c:1078

but task is already holding lock:
ffffffff8fa72248 (rtnl_mutex){+.+.}-{3:3}, at: do_ip_setsockopt+0x127d/0x3cd0 net/ipv4/ip_sockglue.c:1077

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (rtnl_mutex){+.+.}-{3:3}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5759
       __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:2061 [inline]
       __sys_connect+0x2df/0x310 net/socket.c:2078
       __do_sys_connect net/socket.c:2088 [inline]
       __se_sys_connect net/socket.c:2085 [inline]
       __x64_sys_connect+0x7a/0x90 net/socket.c:2085
       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 (sk_lock-AF_INET){+.+.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3133 [inline]
       check_prevs_add kernel/locking/lockdep.c:3252 [inline]
       validate_chain+0x18e0/0x5900 kernel/locking/lockdep.c:3868
       __lock_acquire+0x137a/0x2040 kernel/locking/lockdep.c:5142
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5759
       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:2324
       __sys_setsockopt+0x1ae/0x250 net/socket.c:2347
       __do_sys_setsockopt net/socket.c:2356 [inline]
       __se_sys_setsockopt net/socket.c:2353 [inline]
       __x64_sys_setsockopt+0xb5/0xd0 net/socket.c:2353
       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(rtnl_mutex);
                               lock(sk_lock-AF_INET);
                               lock(rtnl_mutex);
  lock(sk_lock-AF_INET);

 *** DEADLOCK ***

1 lock held by syz-executor266/5220:
 #0: ffffffff8fa72248 (rtnl_mutex){+.+.}-{3:3}, at: do_ip_setsockopt+0x127d/0x3cd0 net/ipv4/ip_sockglue.c:1077

stack backtrace:
CPU: 1 UID: 0 PID: 5220 Comm: syz-executor266 Not tainted 6.11.0-rc4-syzkaller-00255-gd2bafcf224f3 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:93 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:119
 check_noncircular+0x36a/0x4a0 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+0x18e0/0x5900 kernel/locking/lockdep.c:3868
 __lock_acquire+0x137a/0x2040 kernel/locking/lockdep.c:5142
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5759
 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:2324
 __sys_setsockopt+0x1ae/0x250 net/socket.c:2347
 __do_sys_setsockopt net/socket.c:2356 [inline]
 __se_sys_setsockopt net/socket.c:2353 [inline]
 __x64_sys_setsockopt+0xb5/0xd0 net/socket.c:2353
 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: 0033:0x7f9dbe0ada79
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 c1 17 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:00007ffcf0f564e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f9dbe0ada79
RDX: 0000000000000023 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00007f9dbe1205f0 R08: 0000000000000000 R09: 0000000000000006
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 431bde82d7b634db R14: 0000000000000001 R15: 0000000000000001
 </TASK>


---
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.