af_unix: Fix a data-race in unix_dgram_peer_wake_me().

unix_dgram_poll() calls unix_dgram_peer_wake_me() without `other`'s
lock held and check if its receive queue is full.  Here we need to
use unix_recvq_full_lockless() instead of unix_recvq_full(), otherwise
KCSAN will report a data-race.

Fixes: ebc9ffbf8a17 ("unix: avoid use-after-free in ep_remove_wait_queue")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20220605232325.11804-1-kuniyu@amazon.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 654dcef7cfb3849463be9d905ae625319fbae406..2206e6f8902d78a97cba87d52e7696f43b35bec6 100644 (file)
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -490,7 +490,7 @@ static int unix_dgram_peer_wake_me(struct sock *sk, struct sock *other)
         * -ECONNREFUSED. Otherwise, if we haven't queued any skbs
         * to other and its full, we will hang waiting for POLLOUT.
         */
-       if (unix_recvq_full(other) && !sock_flag(other, SOCK_DEAD))
+       if (unix_recvq_full_lockless(other) && !sock_flag(other, SOCK_DEAD))
                return 1;
 
        if (connected)