netfilter: nf_ct_ftp: fix out of bounds read in update_nl_seq()
As noticed by Dan Carpenter <error27@gmail.com>, update_nl_seq()
currently contains an out of bounds read of the seq_aft_nl array
when looking for the oldest sequence number position.
Fix it to only compare valid positions.
Cc: stable@kernel.org
Signed-off-by: Patrick McHardy <kaber@trash.net>
diff --git a/net/netfilter/nf_conntrack_ftp.c b/net/netfilter/nf_conntrack_ftp.c
index 38ea7ef..f0732aa 100644
--- a/net/netfilter/nf_conntrack_ftp.c
+++ b/net/netfilter/nf_conntrack_ftp.c
@@ -323,24 +323,24 @@
struct nf_ct_ftp_master *info, int dir,
struct sk_buff *skb)
{
- unsigned int i, oldest = NUM_SEQ_TO_REMEMBER;
+ unsigned int i, oldest;
/* Look for oldest: if we find exact match, we're done. */
for (i = 0; i < info->seq_aft_nl_num[dir]; i++) {
if (info->seq_aft_nl[dir][i] == nl_seq)
return;
-
- if (oldest == info->seq_aft_nl_num[dir] ||
- before(info->seq_aft_nl[dir][i],
- info->seq_aft_nl[dir][oldest]))
- oldest = i;
}
if (info->seq_aft_nl_num[dir] < NUM_SEQ_TO_REMEMBER) {
info->seq_aft_nl[dir][info->seq_aft_nl_num[dir]++] = nl_seq;
- } else if (oldest != NUM_SEQ_TO_REMEMBER &&
- after(nl_seq, info->seq_aft_nl[dir][oldest])) {
- info->seq_aft_nl[dir][oldest] = nl_seq;
+ } else {
+ if (before(info->seq_aft_nl[dir][0], info->seq_aft_nl[dir][1]))
+ oldest = 0;
+ else
+ oldest = 1;
+
+ if (after(nl_seq, info->seq_aft_nl[dir][oldest]))
+ info->seq_aft_nl[dir][oldest] = nl_seq;
}
}