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-rw-r--r--net/unix/unix_bpf.c21
1 files changed, 18 insertions, 3 deletions
diff --git a/net/unix/unix_bpf.c b/net/unix/unix_bpf.c
index 7ea7c3a0d0d0..bd84785bf8d6 100644
--- a/net/unix/unix_bpf.c
+++ b/net/unix/unix_bpf.c
@@ -161,15 +161,30 @@ int unix_stream_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool r
{
struct sock *sk_pair;
+ /* Restore does not decrement the sk_pair reference yet because we must
+ * keep the a reference to the socket until after an RCU grace period
+ * and any pending sends have completed.
+ */
if (restore) {
sk->sk_write_space = psock->saved_write_space;
sock_replace_proto(sk, psock->sk_proto);
return 0;
}
- sk_pair = unix_peer(sk);
- sock_hold(sk_pair);
- psock->sk_pair = sk_pair;
+ /* psock_update_sk_prot can be called multiple times if psock is
+ * added to multiple maps and/or slots in the same map. There is
+ * also an edge case where replacing a psock with itself can trigger
+ * an extra psock_update_sk_prot during the insert process. So it
+ * must be safe to do multiple calls. Here we need to ensure we don't
+ * increment the refcnt through sock_hold many times. There will only
+ * be a single matching destroy operation.
+ */
+ if (!psock->sk_pair) {
+ sk_pair = unix_peer(sk);
+ sock_hold(sk_pair);
+ psock->sk_pair = sk_pair;
+ }
+
unix_stream_bpf_check_needs_rebuild(psock->sk_proto);
sock_replace_proto(sk, &unix_stream_bpf_prot);
return 0;