Re: [2.6 patch] net/llc/llc_conn.c: fix possible NULL dereference

[Eugene Teo <eteo@redhat.com>]

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Randy Dunlap wrote:
> On Sat, 19 May 2007 13:13:07 +0800 Eugene Teo wrote:
> 
>> skb_peek() might return an empty list. skb should be checked before calling
>> llc_pdu_sn_hdr() with it.
>>
>> Spotted by the Coverity checker.
>>
>> Signed-off-by: Eugene Teo <eteo@redhat.com>
[...]
> 
> Oh, and your patch has spaces instead of tabs.  It's a hassle to
> get thunderbird to send a patch that preserves tabs.  See if this:
>    http://mbligh.org/linuxdocs/Email/Clients/Thunderbird
> helps you any.

Here's a resend:

skb_peek() might return an empty list. skb should be checked before calling
llc_pdu_sn_hdr() with it.

Spotted by the Coverity checker.

Signed-off-by: Eugene Teo <eteo@redhat.com>

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diff --git a/net/llc/llc_conn.c b/net/llc/llc_conn.c
index 3b8cfbe..6d3a07e 100644
--- a/net/llc/llc_conn.c
+++ b/net/llc/llc_conn.c
@@ -324,6 +324,8 @@ int llc_conn_remove_acked_pdus(struct sock *sk, u8 nr, u16 *how_many_unacked)
 	if (!q_len)
 		goto out;
 	skb = skb_peek(&llc->pdu_unack_q);
+	if (!skb)
+		goto out;
 	pdu = llc_pdu_sn_hdr(skb);
 
 	/* finding position of last acked pdu in queue */