tcp: fix potential memory corruption

Imagine initial value of max_skb_frags is 17, and last
skb in write queue has 15 frags.

Then max_skb_frags is lowered to 14 or smaller value.

tcp_sendmsg() will then be allowed to add additional page frags
and eventually go past MAX_SKB_FRAGS, overflowing struct
skb_shared_info.

Fixes: 5f74f82ea3 ("net:Add sysctl_max_skb_frags")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Hans Westgaard Ry <hans.westgaard.ry@oracle.com>
Cc: Håkon Bugge <haakon.bugge@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2016-11-02 07:53:17 -07:00 committed by David S. Miller
parent 9512925a2c
commit ac9e70b17e

View File

@ -1241,7 +1241,7 @@ new_segment:
if (!skb_can_coalesce(skb, i, pfrag->page,
pfrag->offset)) {
if (i == sysctl_max_skb_frags || !sg) {
if (i >= sysctl_max_skb_frags || !sg) {
tcp_mark_push(tp, skb);
goto new_segment;
}