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Commit cc9b17ad authored by Jason Wang's avatar Jason Wang Committed by David S. Miller
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net: sock: validate data_len before allocating skb in sock_alloc_send_pskb() 



We need to validate the number of pages consumed by data_len, otherwise frags
array could be overflowed by userspace. So this patch validate data_len and
return -EMSGSIZE when data_len may occupies more frags than MAX_SKB_FRAGS.

Signed-off-by: default avatarJason Wang <jasowang@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 914bec10

net/core/sock.c

+5 −2
Original line number Diff line number Diff line
@@ -1592,6 +1592,11 @@ struct sk_buff *sock_alloc_send_pskb(struct sock *sk, unsigned long header_len, 
	gfp_t gfp_mask;

	long timeo;

	int err;

	int npages = (data_len + (PAGE_SIZE - 1)) >> PAGE_SHIFT;



	err = -EMSGSIZE;

	if (npages > MAX_SKB_FRAGS)

		goto failure;



	gfp_mask = sk->sk_allocation;

	if (gfp_mask & __GFP_WAIT)
@@ -1610,14 +1615,12 @@ struct sk_buff *sock_alloc_send_pskb(struct sock *sk, unsigned long header_len, 
		if (atomic_read(&sk->sk_wmem_alloc) < sk->sk_sndbuf) {

			skb = alloc_skb(header_len, gfp_mask);

			if (skb) {

				int npages;

				int i;



				/* No pages, we're done... */

				if (!data_len)

					break;



				npages = (data_len + (PAGE_SIZE - 1)) >> PAGE_SHIFT;

				skb->truesize += data_len;

				skb_shinfo(skb)->nr_frags = npages;

				for (i = 0; i < npages; i++) {