diff mbox

[v3] net: check packet payload length

Message ID 1456919998-27680-1-git-send-email-ppandit@redhat.com (mailing list archive)
State New, archived
Headers show

Commit Message

Prasad Pandit March 2, 2016, 11:59 a.m. UTC 
From: Prasad J Pandit <pjp@fedoraproject.org>

While computing IP checksum, 'net_checksum_calculate' reads
payload length from the packet. It could exceed the given 'data'
buffer size. Add a check to avoid it.

Reported-by: Liu Ling <liuling-it@360.cn>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
---
 net/checksum.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

Update as per review:
  -> https://lists.gnu.org/archive/html/qemu-devel/2016-02/msg06121.html

Comments

Jason Wang March 3, 2016, 7:26 a.m. UTC | #1 
On 03/02/2016 07:59 PM, P J P wrote:
> From: Prasad J Pandit <pjp@fedoraproject.org>
>
> While computing IP checksum, 'net_checksum_calculate' reads
> payload length from the packet. It could exceed the given 'data'
> buffer size. Add a check to avoid it.
>
> Reported-by: Liu Ling <liuling-it@360.cn>
> Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
> ---
>  net/checksum.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
>
> Update as per review:
>   -> https://lists.gnu.org/archive/html/qemu-devel/2016-02/msg06121.html
>
> diff --git a/net/checksum.c b/net/checksum.c
> index 14c0855..0942437 100644
> --- a/net/checksum.c
> +++ b/net/checksum.c
> @@ -59,6 +59,11 @@ void net_checksum_calculate(uint8_t *data, int length)
>      int hlen, plen, proto, csum_offset;
>      uint16_t csum;
>  
> +    /* Ensure data has complete L2 & L3 headers. */
> +    if (length < 14 + 20) {
> +        return;
> +    }
> +
>      if ((data[14] & 0xf0) != 0x40)
>  	return; /* not IPv4 */
>      hlen  = (data[14] & 0x0f) * 4;
> @@ -76,8 +81,9 @@ void net_checksum_calculate(uint8_t *data, int length)
>  	return;
>      }
>  
> -    if (plen < csum_offset+2)
> -	return;
> +    if (plen < csum_offset + 2 || 14 + hlen + plen > length) {
> +        return;
> +    }
>  
>      data[14+hlen+csum_offset]   = 0;
>      data[14+hlen+csum_offset+1] = 0;

Applied to -net.

Thanks
diff mbox

Patch

diff --git a/net/checksum.c b/net/checksum.c
index 14c0855..0942437 100644
--- a/net/checksum.c
+++ b/net/checksum.c
@@ -59,6 +59,11 @@  void net_checksum_calculate(uint8_t *data, int length)
     int hlen, plen, proto, csum_offset;
     uint16_t csum;
 
+    /* Ensure data has complete L2 & L3 headers. */
+    if (length < 14 + 20) {
+        return;
+    }
+
     if ((data[14] & 0xf0) != 0x40)
 	return; /* not IPv4 */
     hlen  = (data[14] & 0x0f) * 4;
@@ -76,8 +81,9 @@  void net_checksum_calculate(uint8_t *data, int length)
 	return;
     }
 
-    if (plen < csum_offset+2)
-	return;
+    if (plen < csum_offset + 2 || 14 + hlen + plen > length) {
+        return;
+    }
 
     data[14+hlen+csum_offset]   = 0;
     data[14+hlen+csum_offset+1] = 0;