Eric Dumazet <eduma...@google.com> wrote:
> When either "goto wait_interrupted;" or "goto wait_error;"
> paths are taken, socket lock has already been released.
>
> This patch fixes following syzbot splat :
>
> WARNING: bad unlock balance detected!
> 5.0.0-rc4+ #59 Not tainted
> -------------------------------------
> syz-executor223/8256 is trying to release lock (sk_lock-AF_RXRPC) at:
> [<ffffffff86651353>] rxrpc_recvmsg+0x6d3/0x3099 net/rxrpc/recvmsg.c:598
> but there are no more locks to release!
>
> other info that might help us debug this:
> 1 lock held by syz-executor223/8256:
> #0: 00000000fa9ed0f4 (slock-AF_RXRPC){+...}, at: spin_lock_bh
> include/linux/spinlock.h:334 [inline]
> #0: 00000000fa9ed0f4 (slock-AF_RXRPC){+...}, at: release_sock+0x20/0x1c0
> net/core/sock.c:2798
>
> stack backtrace:
> CPU: 1 PID: 8256 Comm: syz-executor223 Not tainted 5.0.0-rc4+ #59
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Call Trace:
> __dump_stack lib/dump_stack.c:77 [inline]
> dump_stack+0x172/0x1f0 lib/dump_stack.c:113
> print_unlock_imbalance_bug kernel/locking/lockdep.c:3391 [inline]
> print_unlock_imbalance_bug.cold+0x114/0x123 kernel/locking/lockdep.c:3368
> __lock_release kernel/locking/lockdep.c:3601 [inline]
> lock_release+0x67e/0xa00 kernel/locking/lockdep.c:3860
> sock_release_ownership include/net/sock.h:1471 [inline]
> release_sock+0x183/0x1c0 net/core/sock.c:2808
> rxrpc_recvmsg+0x6d3/0x3099 net/rxrpc/recvmsg.c:598
> sock_recvmsg_nosec net/socket.c:794 [inline]
> sock_recvmsg net/socket.c:801 [inline]
> sock_recvmsg+0xd0/0x110 net/socket.c:797
> __sys_recvfrom+0x1ff/0x350 net/socket.c:1845
> __do_sys_recvfrom net/socket.c:1863 [inline]
> __se_sys_recvfrom net/socket.c:1859 [inline]
> __x64_sys_recvfrom+0xe1/0x1a0 net/socket.c:1859
> do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x446379
> Code: e8 2c b3 02 00 48 83 c4 18 c3 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 0f
> 83 2b 09 fc ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:00007fe5da89fd98 EFLAGS: 00000246 ORIG_RAX: 000000000000002d
> RAX: ffffffffffffffda RBX: 00000000006dbc28 RCX: 0000000000446379
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
> RBP: 00000000006dbc20 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc2c
> R13: 0000000000000000 R14: 0000000000000000 R15: 20c49ba5e353f7cf
>
> Fixes: 248f219cb8bc ("rxrpc: Rewrite the data and ack handling code")
> Signed-off-by: Eric Dumazet <eduma...@google.com>
> Cc: David Howells <dhowe...@redhat.com>
> Reported-by: syzbot <syzkal...@googlegroups.com>
Acked-by: David Howells <dhowe...@redhat.com>
