[PATCH 4.14 169/205] rxrpc: bad unlock balance in rxrpc_recvmsg

Greg Kroah-Hartman
2019-02-11T15:02:25Z

From: Eric Dumazet <edumazet@google.com>

[ Upstream commit 6dce3c20ac429e7a651d728e375853370c796e8d ]

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 <edumazet@google.com>
Cc: David Howells <dhowells@redhat.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/rxrpc/recvmsg.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/rxrpc/recvmsg.c
+++ b/net/rxrpc/recvmsg.c
@@ -588,6 +588,7 @@ error_requeue_call:
}
error_no_call:
release_sock(&rx->sk);
+error_trace:
trace_rxrpc_recvmsg(call, rxrpc_recvmsg_return, 0, 0, 0, ret);
return ret;

@@ -596,7 +597,7 @@ wait_interrupted:
wait_error:
finish_wait(sk_sleep(&rx->sk), &wait);
call = NULL;
- goto error_no_call;
+ goto error_trace;
}

/**