2017-04-25, 17:23:00 +0200, Jason A. Donenfeld wrote:
> We call skb_cow_data, which is good anyway to ensure we can actually
> modify the skb as such (another error from prior). Now that we have the
> number of fragments required, we can safely allocate exactly that amount
> of memory.
>
> Signed-off-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
> Cc: Sabrina Dubroca <sd@xxxxxxxxxxxxxxx>
> Cc: security@xxxxxxxxxx
> Cc: stable@xxxxxxxxxxxxxxx
> ---
> drivers/net/macsec.c | 25 ++++++++++++++++++++-----
> 1 file changed, 20 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/net/macsec.c b/drivers/net/macsec.c
> index dbab05afcdbe..56dafdee4c9c 100644
> --- a/drivers/net/macsec.c
> +++ b/drivers/net/macsec.c
[...]
> @@ -917,6 +926,7 @@ static struct sk_buff *macsec_decrypt(struct sk_buff *skb,
> {
> int ret;
> struct scatterlist *sg;
> + struct sk_buff *trailer;
> unsigned char *iv;
> struct aead_request *req;
> struct macsec_eth_header *hdr;
> @@ -927,7 +937,12 @@ static struct sk_buff *macsec_decrypt(struct sk_buff *skb,
> if (!skb)
> return ERR_PTR(-ENOMEM);
>
> - req = macsec_alloc_req(rx_sa->key.tfm, &iv, &sg);
> + ret = skb_cow_data(skb, 0, &trailer);
> + if (unlikely(ret < 0)) {
> + kfree_skb(skb);
> + return ERR_PTR(ret);
> + }
> + req = macsec_alloc_req(rx_sa->key.tfm, &iv, &sg, ret);
> if (!req) {
> kfree_skb(skb);
> return ERR_PTR(-ENOMEM);
There's a problem here (and in macsec_encrypt): you need to update the
call to sg_init_table, like I did in my patch. Otherwise,
sg_init_table() is going to access sg[MAX_SKB_FRAGS], which may be
past what you allocated.
How did you test this? ;)
--
Sabrina