Re: [syzbot] Re: [syzbot] [net?] possible deadlock in rtnl_lock (8)

[syzbot <syzbot+51cf7cc5f9ffc1006ef2@syzkaller.appspotmail.com>]

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Subject: Re: [syzbot] [net?] possible deadlock in rtnl_lock (8)
Author: alibuda@linux.alibaba.com



On 8/19/24 11:49 AM, syzbot wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    1fb918967b56 Merge tag 'for-6.11-rc3-tag' of git://git.ker..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=129dd7d9980000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=804764788c03071f
> dashboard link: https://syzkaller.appspot.com/bug?extid=51cf7cc5f9ffc1006ef2
> compiler:       aarch64-linux-gnu-gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
> userspace arch: arm64
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> Downloadable assets:
> disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/384ffdcca292/non_bootable_disk-1fb91896.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/7b8fac7b5b8b/vmlinux-1fb91896.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/676950a147e6/Image-1fb91896.gz.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+51cf7cc5f9ffc1006ef2@syzkaller.appspotmail.com
>
> ======================================================
> WARNING: possible circular locking dependency detected
> 6.11.0-rc3-syzkaller-00066-g1fb918967b56 #0 Not tainted
> ------------------------------------------------------
> syz.0.5481/17612 is trying to acquire lock:
> ffff8000880033a8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock+0x1c/0x28 net/core/rtnetlink.c:79
>
> but task is already holding lock:
> ffff000010332b50 (&smc->clcsock_release_lock){+.+.}-{3:3}, at: smc_setsockopt+0xd8/0xcec 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}:
>         __mutex_lock_common kernel/locking/mutex.c:608 [inline]
>         __mutex_lock+0x134/0x840 kernel/locking/mutex.c:752
>         mutex_lock_nested+0x24/0x30 kernel/locking/mutex.c:804
>         smc_switch_to_fallback+0x34/0x80c net/smc/af_smc.c:902
>         smc_sendmsg+0xe4/0x8f8 net/smc/af_smc.c:2779
>         sock_sendmsg_nosec net/socket.c:730 [inline]
>         __sock_sendmsg+0xc8/0x168 net/socket.c:745
>         __sys_sendto+0x1a8/0x254 net/socket.c:2204
>         __do_sys_sendto net/socket.c:2216 [inline]
>         __se_sys_sendto net/socket.c:2212 [inline]
>         __arm64_sys_sendto+0xc0/0x134 net/socket.c:2212
>         __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
>         invoke_syscall+0x6c/0x258 arch/arm64/kernel/syscall.c:49
>         el0_svc_common.constprop.0+0xac/0x230 arch/arm64/kernel/syscall.c:132
>         do_el0_svc+0x40/0x58 arch/arm64/kernel/syscall.c:151
>         el0_svc+0x50/0x180 arch/arm64/kernel/entry-common.c:712
>         el0t_64_sync_handler+0x100/0x12c arch/arm64/kernel/entry-common.c:730
>         el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598
>
> -> #1 (sk_lock-AF_INET){+.+.}-{0:0}:
>         lock_sock_nested+0x38/0xe8 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+0x58/0x74 net/core/sock.c:1052
>         do_ip_setsockopt+0xe0/0x2358 net/ipv4/ip_sockglue.c:1078
>         ip_setsockopt+0x34/0x9c net/ipv4/ip_sockglue.c:1417
>         raw_setsockopt+0x7c/0x2e0 net/ipv4/raw.c:845
>         sock_common_setsockopt+0x70/0xe0 net/core/sock.c:3735
>         do_sock_setsockopt+0x17c/0x354 net/socket.c:2324
>         __sys_setsockopt+0xdc/0x178 net/socket.c:2347
>         __do_sys_setsockopt net/socket.c:2356 [inline]
>         __se_sys_setsockopt net/socket.c:2353 [inline]
>         __arm64_sys_setsockopt+0xa4/0x100 net/socket.c:2353
>         __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
>         invoke_syscall+0x6c/0x258 arch/arm64/kernel/syscall.c:49
>         el0_svc_common.constprop.0+0xac/0x230 arch/arm64/kernel/syscall.c:132
>         do_el0_svc+0x40/0x58 arch/arm64/kernel/syscall.c:151
>         el0_svc+0x50/0x180 arch/arm64/kernel/entry-common.c:712
>         el0t_64_sync_handler+0x100/0x12c arch/arm64/kernel/entry-common.c:730
>         el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598
>
> -> #0 (rtnl_mutex){+.+.}-{3:3}:
>         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+0x2aa4/0x6340 kernel/locking/lockdep.c:5142
>         lock_acquire kernel/locking/lockdep.c:5759 [inline]
>         lock_acquire+0x48c/0x7a4 kernel/locking/lockdep.c:5724
>         __mutex_lock_common kernel/locking/mutex.c:608 [inline]
>         __mutex_lock+0x134/0x840 kernel/locking/mutex.c:752
>         mutex_lock_nested+0x24/0x30 kernel/locking/mutex.c:804
>         rtnl_lock+0x1c/0x28 net/core/rtnetlink.c:79
>         do_ipv6_setsockopt+0x1a04/0x3814 net/ipv6/ipv6_sockglue.c:566
>         ipv6_setsockopt+0xc8/0x140 net/ipv6/ipv6_sockglue.c:993
>         tcp_setsockopt+0x90/0xcc net/ipv4/tcp.c:3768
>         sock_common_setsockopt+0x70/0xe0 net/core/sock.c:3735
>         smc_setsockopt+0x150/0xcec net/smc/af_smc.c:3072
>         do_sock_setsockopt+0x17c/0x354 net/socket.c:2324
>         __sys_setsockopt+0xdc/0x178 net/socket.c:2347
>         __do_sys_setsockopt net/socket.c:2356 [inline]
>         __se_sys_setsockopt net/socket.c:2353 [inline]
>         __arm64_sys_setsockopt+0xa4/0x100 net/socket.c:2353
>         __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
>         invoke_syscall+0x6c/0x258 arch/arm64/kernel/syscall.c:49
>         el0_svc_common.constprop.0+0xac/0x230 arch/arm64/kernel/syscall.c:132
>         do_el0_svc+0x40/0x58 arch/arm64/kernel/syscall.c:151
>         el0_svc+0x50/0x180 arch/arm64/kernel/entry-common.c:712
>         el0t_64_sync_handler+0x100/0x12c arch/arm64/kernel/entry-common.c:730
>         el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598
>
> 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.0.5481/17612:
>   #0: ffff000010332b50 (&smc->clcsock_release_lock){+.+.}-{3:3}, at: smc_setsockopt+0xd8/0xcec net/smc/af_smc.c:3064
>
> stack backtrace:
> CPU: 1 UID: 0 PID: 17612 Comm: syz.0.5481 Not tainted 6.11.0-rc3-syzkaller-00066-g1fb918967b56 #0
> Hardware name: linux,dummy-virt (DT)
> Call trace:
>   dump_backtrace+0x9c/0x11c arch/arm64/kernel/stacktrace.c:317
>   show_stack+0x18/0x24 arch/arm64/kernel/stacktrace.c:324
>   __dump_stack lib/dump_stack.c:93 [inline]
>   dump_stack_lvl+0xa4/0xf4 lib/dump_stack.c:119
>   dump_stack+0x1c/0x28 lib/dump_stack.c:128
>   print_circular_bug+0x420/0x6f8 kernel/locking/lockdep.c:2059
>   check_noncircular+0x2dc/0x364 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+0x2aa4/0x6340 kernel/locking/lockdep.c:5142
>   lock_acquire kernel/locking/lockdep.c:5759 [inline]
>   lock_acquire+0x48c/0x7a4 kernel/locking/lockdep.c:5724
>   __mutex_lock_common kernel/locking/mutex.c:608 [inline]
>   __mutex_lock+0x134/0x840 kernel/locking/mutex.c:752
>   mutex_lock_nested+0x24/0x30 kernel/locking/mutex.c:804
>   rtnl_lock+0x1c/0x28 net/core/rtnetlink.c:79
>   do_ipv6_setsockopt+0x1a04/0x3814 net/ipv6/ipv6_sockglue.c:566
>   ipv6_setsockopt+0xc8/0x140 net/ipv6/ipv6_sockglue.c:993
>   tcp_setsockopt+0x90/0xcc net/ipv4/tcp.c:3768
>   sock_common_setsockopt+0x70/0xe0 net/core/sock.c:3735
>   smc_setsockopt+0x150/0xcec net/smc/af_smc.c:3072
>   do_sock_setsockopt+0x17c/0x354 net/socket.c:2324
>   __sys_setsockopt+0xdc/0x178 net/socket.c:2347
>   __do_sys_setsockopt net/socket.c:2356 [inline]
>   __se_sys_setsockopt net/socket.c:2353 [inline]
>   __arm64_sys_setsockopt+0xa4/0x100 net/socket.c:2353
>   __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
>   invoke_syscall+0x6c/0x258 arch/arm64/kernel/syscall.c:49
>   el0_svc_common.constprop.0+0xac/0x230 arch/arm64/kernel/syscall.c:132
>   do_el0_svc+0x40/0x58 arch/arm64/kernel/syscall.c:151
>   el0_svc+0x50/0x180 arch/arm64/kernel/entry-common.c:712
>   el0t_64_sync_handler+0x100/0x12c arch/arm64/kernel/entry-common.c:730
>   el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598
>
>
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@googlegroups.com.
>
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
>
> 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:
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>
> If you want to undo deduplication, reply with:
> #syz undup

#syz test

diff --git a/net/smc/smc_inet.c b/net/smc/smc_inet.c
index bece346..281f0450 100644
--- a/net/smc/smc_inet.c
+++ b/net/smc/smc_inet.c
@@ -102,14 +102,29 @@
  };
  #endif /* CONFIG_IPV6 */

+static struct lock_class_key smc_clcsk_slock_keys[2];
+static struct lock_class_key smc_clcsk_keys[2];
+
  static int smc_inet_init_sock(struct sock *sk)
  {
+   bool is_ipv6 = sk->sk_family == AF_INET6;
     struct net *net = sock_net(sk);
+   int rc;

     /* init common smc sock */
     smc_sk_init(net, sk, IPPROTO_SMC);
     /* create clcsock */
-   return smc_create_clcsk(net, sk, sk->sk_family);
+   rc = smc_create_clcsk(net, sk, sk->sk_family);
+   if (rc)
+       return rc;
+
+   sock_lock_init_class_and_name(smc_sk(sk)->clcsk,
+                     is_ipv6 ? "slock-AF_INET6-SMC-CLCSK" : 
"slock-AF_INET-SMC-CLCSK",
+                     &smc_clcsk_slock_keys[is_ipv6],
+                     is_ipv6 ? "sk_lock-AF_INET6-SMC-CLCSK" : 
"sk_lock-AF_INET-SMC-CLCSK",
+                     &smc_clcsk_keys[is_ipv6]);
+
+   return 0;
  }

  int __init smc_inet_init(void)
--
1.8.3.1