From: Gao Feng <f...@ikuai8.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 <f...@ikuai8.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


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