From patchwork Wed Jul 11 19:42:12 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [1/1, HARDY, CVE-2012-2136] net: sock: validate data_len before allocating skb in sock_alloc_send_pskb() Date: Wed, 11 Jul 2012 09:42:12 -0000 From: Brad Figg X-Patchwork-Id: 170507 Message-Id: <1342035733-23595-2-git-send-email-brad.figg@canonical.com> To: kernel-team@lists.ubuntu.com From: Jason Wang CVE-2012-2136 BugLink: http://bugs.launchpad.net/bugs/1006622 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 Signed-off-by: David S. Miller (cherry picked from commit cc9b17ad29ecaa20bfe426a8d4dbfb94b13ff1cc) Signed-off-by: Brad Figg --- debian/binary-custom.d/xen/src/net/core/sock.c | 7 +++++-- net/core/sock.c | 7 +++++-- 2 files changed, 10 insertions(+), 4 deletions(-) diff --git a/debian/binary-custom.d/xen/src/net/core/sock.c b/debian/binary-custom.d/xen/src/net/core/sock.c index b0e5208..a39b6aa 100644 --- a/debian/binary-custom.d/xen/src/net/core/sock.c +++ b/debian/binary-custom.d/xen/src/net/core/sock.c @@ -1233,6 +1233,11 @@ static struct sk_buff *sock_alloc_send_pskb(struct sock *sk, 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) @@ -1251,14 +1256,12 @@ static struct sk_buff *sock_alloc_send_pskb(struct sock *sk, 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++) { diff --git a/net/core/sock.c b/net/core/sock.c index b0e5208..a39b6aa 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -1233,6 +1233,11 @@ static struct sk_buff *sock_alloc_send_pskb(struct sock *sk, 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) @@ -1251,14 +1256,12 @@ static struct sk_buff *sock_alloc_send_pskb(struct sock *sk, 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++) {