Commit f75e3eb0 authored by Jason A. Donenfeld's avatar Jason A. Donenfeld Committed by Jakub Kicinski
Browse files

wireguard: send: append trailer after expanding head 



With how this is currently written, we add the trailer, zero it out, and
then add the header space on. If that header space requires a
reallocation + copy, the zeros in the trailer aren't copied, because the
skb len hasn't actually been yet expanded to cover that. Instead add the
padding at the end of the process rather than at the beginning.

Fixes: e7096c13 ("net: WireGuard secure network tunnel")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarJason A. Donenfeld <Jason@zx2c4.com>
Link: https://patch.msgid.link/20260529173134.3080773-2-Jason@zx2c4.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 072aa0f5

drivers/net/wireguard/send.c

+10 −10
Original line number Diff line number Diff line
@@ -177,16 +177,6 @@ static bool encrypt_packet(struct sk_buff *skb, struct noise_keypair *keypair) 
	trailer_len = padding_len + noise_encrypted_len(0);

	plaintext_len = skb->len + padding_len;



	/* Expand data section to have room for padding and auth tag. */

	num_frags = skb_cow_data(skb, trailer_len, &trailer);

	if (unlikely(num_frags < 0 || num_frags > ARRAY_SIZE(sg)))

		return false;



	/* Set the padding to zeros, and make sure it and the auth tag are part

	 * of the skb.

	 */

	memset(skb_tail_pointer(trailer), 0, padding_len);



	/* Expand head section to have room for our header and the network

	 * stack's headers.

	 */
@@ -198,6 +188,16 @@ static bool encrypt_packet(struct sk_buff *skb, struct noise_keypair *keypair) 
		     skb_checksum_help(skb)))

		return false;



	/* Expand data section to have room for padding and auth tag. */

	num_frags = skb_cow_data(skb, trailer_len, &trailer);

	if (unlikely(num_frags < 0 || num_frags > ARRAY_SIZE(sg)))

		return false;



	/* Set the padding to zeros, and make sure it and the auth tag are part

	 * of the skb.

	 */

	memset(skb_tail_pointer(trailer), 0, padding_len);



	/* Only after checksumming can we safely add on the padding at the end

	 * and the header.

	 */