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net: sock: validate data_len before allocating skb in sock_alloc_send_pskb()

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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: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jason Wang 2012-05-30 21:18:10 +00:00 committed by David S. Miller
parent 914bec1011
commit cc9b17ad29
1 changed files with 5 additions and 2 deletions
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7
net/core/sock.c
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@ -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++) {