From 3a8dd9711e0792f64394edafadd66c2d1f1904df Mon Sep 17 00:00:00 2001
From: Willem de Bruijn <willemb@google.com>
Date: Wed, 11 Mar 2015 15:43:55 -0400
Subject: [PATCH] sock: fix possible NULL sk dereference in __skb_tstamp_tx
Test that sk != NULL before reading sk->sk_tsflags.
Fixes: 49ca0d8bfaf3 ("net-timestamp: no-payload option")
Reported-by: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
net/core/skbuff.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 434e78e5254d..8e4ac97c8477 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3733,9 +3733,13 @@ void __skb_tstamp_tx(struct sk_buff *orig_skb,
struct sock *sk, int tstype)
{
struct sk_buff *skb;
- bool tsonly = sk->sk_tsflags & SOF_TIMESTAMPING_OPT_TSONLY;
+ bool tsonly;
- if (!sk || !skb_may_tx_timestamp(sk, tsonly))
+ if (!sk)
+ return;
+
+ tsonly = sk->sk_tsflags & SOF_TIMESTAMPING_OPT_TSONLY;
+ if (!skb_may_tx_timestamp(sk, tsonly))
return;
if (tsonly)