[PATCH net] tcp: ulp: fix possible crash in tcp_diag_get_aux_size()

[Eric Dumazet]

tcp_diag_get_aux_size() can be called with sockets in any state.

icsk_ulp_ops is only present for full sockets.

For SYN_RECV or TIME_WAIT ones we would access garbage.

Fixes: 61723b393292 ("tcp: ulp: add functions to dump ulp-specific information")
Signed-off-by: Eric Dumazet <eduma...@google.com>
Reported-by: Luke Hsiao <lukehs...@google.com>
Reported-by: Neal Cardwell <ncardw...@google.com>
Cc: Davide Caratti <dcara...@redhat.com>
---
 net/ipv4/tcp_diag.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/tcp_diag.c b/net/ipv4/tcp_diag.c
index 
babc156deabb573f11bba344215d2c3712c4a3cd..81a8221d650a94be53d17354c60ddd0c655eaccf
 100644
--- a/net/ipv4/tcp_diag.c
+++ b/net/ipv4/tcp_diag.c
@@ -163,7 +163,7 @@ static size_t tcp_diag_get_aux_size(struct sock *sk, bool 
net_admin)
        }
 #endif
 
-       if (net_admin) {
+       if (net_admin && sk_fullsock(sk)) {
                const struct tcp_ulp_ops *ulp_ops;
 
                ulp_ops = icsk->icsk_ulp_ops;
-- 
2.23.0.187.g17f5b7556c-goog