netdev - [PATCH v3 nf] netfilter: seqadj: Fix one possible panic in seqadj when mem is exhausted

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Message-Id: <1472903510-16652-1-git-send-email-fgao@ikuai8.com>
Date:   Sat,  3 Sep 2016 19:51:50 +0800
From:   fgao@...ai8.com
To:     pablo@...filter.org, netfilter-devel@...r.kernel.org, fw@...len.de,
        coreteam@...filter.org, netdev@...r.kernel.org
Cc:     gfree.wind@...il.com, Gao Feng <fgao@...ai8.com>
Subject: [PATCH v3 nf] netfilter: seqadj: Fix one possible panic in seqadj when mem is exhausted

From: Gao Feng <fgao@...ai8.com>

When memory is exhausted, nfct_seqadj_ext_add may fail to add the seqadj
extension. But the function nf_ct_seqadj_init doesn't check if get valid
seqadj pointer by the nfct_seqadj, while other functions perform the
sanity check.

So the system would be panic when nfct_seqadj_ext_add failed.

Signed-off-by: Gao Feng <fgao@...ai8.com>
---
 v3: Remove the warning log when seqadj is null;
 v2: Remove the unnessary seqadj check in nf_ct_seq_adjust
 v1: Initial patch

 net/netfilter/nf_conntrack_seqadj.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/netfilter/nf_conntrack_seqadj.c b/net/netfilter/nf_conntrack_seqadj.c
index dff0f0c..7f8d814 100644
--- a/net/netfilter/nf_conntrack_seqadj.c
+++ b/net/netfilter/nf_conntrack_seqadj.c
@@ -16,9 +16,12 @@ int nf_ct_seqadj_init(struct nf_conn *ct, enum ip_conntrack_info ctinfo,
 	if (off == 0)
 		return 0;
 
+	seqadj = nfct_seqadj(ct);
+	if (unlikely(!seqadj))
+		return 0;
+
 	set_bit(IPS_SEQ_ADJUST_BIT, &ct->status);
 
-	seqadj = nfct_seqadj(ct);
 	this_way = &seqadj->seq[dir];
 	this_way->offset_before	 = off;
 	this_way->offset_after	 = off;
-- 
1.9.1