net/tls: don't copy negative amounts of data in reencrypt

There is no guarantee the record starts before the skb frags.
If we don't check for this condition copy amount will get
negative, leading to reads and writes to random memory locations.
Familiar hilarity ensues.

Fixes: 4799ac81e5 ("tls: Add rx inline crypto offload")
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: John Hurley <john.hurley@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jakub Kicinski 2019-04-25 17:35:09 -07:00 committed by David S. Miller
parent b2a20fd072
commit 97e1caa517

View File

@ -628,14 +628,16 @@ static int tls_device_reencrypt(struct sock *sk, struct sk_buff *skb)
else
err = 0;
copy = min_t(int, skb_pagelen(skb) - offset,
rxm->full_len - TLS_CIPHER_AES_GCM_128_TAG_SIZE);
if (skb_pagelen(skb) > offset) {
copy = min_t(int, skb_pagelen(skb) - offset,
rxm->full_len - TLS_CIPHER_AES_GCM_128_TAG_SIZE);
if (skb->decrypted)
skb_store_bits(skb, offset, buf, copy);
if (skb->decrypted)
skb_store_bits(skb, offset, buf, copy);
offset += copy;
buf += copy;
offset += copy;
buf += copy;
}
skb_walk_frags(skb, skb_iter) {
copy = min_t(int, skb_iter->len,