From: WANG Cong <xiyou.wangcong@gmail.com>
Date: Mon, 13 Feb 2017 19:13:16 +0000 (-0800)
Subject: kcm: fix a null pointer dereference in kcm_sendmsg()
X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=cd27b96bc13841ee7af25837a6ae86fee87273d6;p=openwrt%2Fstaging%2Fblogic.git

kcm: fix a null pointer dereference in kcm_sendmsg()

In commit 98e3862ca2b1 ("kcm: fix 0-length case for kcm_sendmsg()")
I tried to avoid skb allocation for 0-length case, but missed
a check for NULL pointer in the non EOR case.

Fixes: 98e3862ca2b1 ("kcm: fix 0-length case for kcm_sendmsg()")
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Tom Herbert <tom@herbertland.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Acked-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c
index 64f0e8531af0..a646f3481240 100644
--- a/net/kcm/kcmsock.c
+++ b/net/kcm/kcmsock.c
@@ -1044,8 +1044,10 @@ wait_for_memory:
 	} else {
 		/* Message not complete, save state */
 partial_message:
-		kcm->seq_skb = head;
-		kcm_tx_msg(head)->last_skb = skb;
+		if (head) {
+			kcm->seq_skb = head;
+			kcm_tx_msg(head)->last_skb = skb;
+		}
 	}
 
 	KCM_STATS_ADD(kcm->stats.tx_bytes, copied);