netdev - [PATCH 1/2 nf] netfilter: seqadj: Fix some possible panics of seqadj when mem is exhausted

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Date:   Fri,  2 Sep 2016 09:48:25 +0800
From:   fgao@...ai8.com
To:     pablo@...filter.org, netfilter-devel@...r.kernel.org,
        coreteam@...filter.org, netdev@...r.kernel.org
Cc:     gfree.wind@...il.com, Gao Feng <fgao@...ai8.com>
Subject: [PATCH 1/2 nf] netfilter: seqadj: Fix some possible panics of 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 these interface functions nf_ct_seqadj_init and
nf_ct_seq_adjust don't check if they get the valid seqadj pointer by the
nfct_seqadj, while nf_ct_seqadj_set and nf_ct_seq_offset perform that
check. So the system would be panic when nfct_seqadj_ext_add failed.

Signed-off-by: Gao Feng <fgao@...ai8.com>
---
 net/netfilter/nf_conntrack_seqadj.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/net/netfilter/nf_conntrack_seqadj.c b/net/netfilter/nf_conntrack_seqadj.c
index dff0f0c..2a2fd0e 100644
--- a/net/netfilter/nf_conntrack_seqadj.c
+++ b/net/netfilter/nf_conntrack_seqadj.c
@@ -16,9 +16,14 @@ 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)) {
+		WARN_ONCE(1, "Missing nfct_seqadj_ext_add() setup call\n");
+		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;
@@ -171,6 +176,11 @@ int nf_ct_seq_adjust(struct sk_buff *skb,
 	struct nf_ct_seqadj *this_way, *other_way;
 	int res;
 
+	if (unlikely(!seqadj)) {
+		WARN_ONCE(1, "Missing nfct_seqadj_ext_add() setup call\n");
+		return 0;
+	}
+
 	this_way  = &seqadj->seq[dir];
 	other_way = &seqadj->seq[!dir];
 
@@ -218,8 +228,10 @@ s32 nf_ct_seq_offset(const struct nf_conn *ct,
 	struct nf_conn_seqadj *seqadj = nfct_seqadj(ct);
 	struct nf_ct_seqadj *this_way;
 
-	if (!seqadj)
+	if (unlikely(!seqadj)) {
+		WARN_ONCE(1, "Missing nfct_seqadj_ext_add() setup call\n");
 		return 0;
+	}
 
 	this_way = &seqadj->seq[dir];
 	return after(seq, this_way->correction_pos) ?
-- 
1.9.1