Dan Carpenter wrote:
> net/netfilter/nf_conntrack_ftp.c
> 321 /* We don't update if it's older than what we have. */
> 322 static void update_nl_seq(struct nf_conn *ct, u32 nl_seq,
> 323 struct nf_ct_ftp_master *info, int dir,
> 324 struct sk_buff *skb)
> 325 {
> 326 unsigned int i, oldest = NUM_SEQ_TO_REMEMBER;
>
> Should this be oldest = NUM_SEQ_TO_REMEMBER - 1;? The array is
> defined as:
> u_int32_t seq_aft_nl[IP_CT_DIR_MAX][NUM_SEQ_TO_REMEMBER];
That would break the logic further down below.
> 327
> 328 /* Look for oldest: if we find exact match, we're done. */
> 329 for (i = 0; i < info->seq_aft_nl_num[dir]; i++) {
> 330 if (info->seq_aft_nl[dir][i] == nl_seq)
> 331 return;
> 332
> 333 if (oldest == info->seq_aft_nl_num[dir] ||
> 334 before(info->seq_aft_nl[dir][i],
> 335 info->seq_aft_nl[dir][oldest]))
>
> Line 335 has the possible array out of bounds I am concerned about.
Good catch, this is definitely a bug. The entire function seems
overly complicated to select one of two possible positions. I'll
commit the attached patch to fix this after some testing.
diff --git a/net/netfilter/nf_conntrack_ftp.c b/net/netfilter/nf_conntrack_ftp.c
index 38ea7ef..44b8d67 100644
--- a/net/netfilter/nf_conntrack_ftp.c
+++ b/net/netfilter/nf_conntrack_ftp.c
@@ -323,24 +323,25 @@ static void update_nl_seq(struct nf_conn *ct, u32 nl_seq,
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;
}
}
