[PATCH 2/2] af_unix: only post SO_INQ cmsg for non-error case

[Jens Axboe <axboe@kernel.dk>]

As is done for TCP sockets, don't post an SCM_INQ cmsg for an error
case. Only post them for the non-error case, which is when
unix_stream_read_generic will return >= 0.

Cc: stable@vger.kernel.org
Fixes: df30285b3670 ("af_unix: Introduce SO_INQ.")
Reported-by: Julian Orth <ju.orth@gmail.com>
Link: https://github.com/axboe/liburing/issues/1509
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 net/unix/af_unix.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 110d716087b5..72dc5d5bcac8 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -3091,7 +3091,7 @@ static int unix_stream_read_generic(struct unix_stream_read_state *state,
 		scm_recv_unix(sock, msg, &scm, flags);
 
 		do_cmsg = READ_ONCE(u->recvmsg_inq);
-		if (do_cmsg || msg->msg_get_inq) {
+		if ((do_cmsg || msg->msg_get_inq) && (copied ?: err) >= 0) {
 			msg->msg_inq = READ_ONCE(u->inq_len);
 			if (do_cmsg)
 				put_cmsg(msg, SOL_SOCKET, SCM_INQ,
-- 
2.51.0