Commit ac9e70b1 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

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

Fixes: 5f74f82e

 ("net:Add sysctl_max_skb_frags")
Signed-off-by: default avatarEric Dumazet <>
Cc: Hans Westgaard Ry <>
Cc: Håkon Bugge <>
Signed-off-by: default avatarDavid S. Miller <>
parent 9512925a
...@@ -1241,7 +1241,7 @@ int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size) ...@@ -1241,7 +1241,7 @@ int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
if (!skb_can_coalesce(skb, i, pfrag->page, if (!skb_can_coalesce(skb, i, pfrag->page,
pfrag->offset)) { pfrag->offset)) {
if (i == sysctl_max_skb_frags || !sg) { if (i >= sysctl_max_skb_frags || !sg) {
tcp_mark_push(tp, skb); tcp_mark_push(tp, skb);
goto new_segment; goto new_segment;
} }
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