* [Qemu-devel] [PATCH v3] net: check packet payload length
@ 2016-03-02 11:59 P J P
2016-03-03 7:26 ` Jason Wang
0 siblings, 1 reply; 2+ messages in thread
From: P J P @ 2016-03-02 11:59 UTC (permalink / raw)
To: Jason Wang; +Cc: Markus Armbruster, Prasad J Pandit, Qemu Developers, Liu Ling
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;
--
2.5.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [Qemu-devel] [PATCH v3] net: check packet payload length
2016-03-02 11:59 [Qemu-devel] [PATCH v3] net: check packet payload length P J P
@ 2016-03-03 7:26 ` Jason Wang
0 siblings, 0 replies; 2+ messages in thread
From: Jason Wang @ 2016-03-03 7:26 UTC (permalink / raw)
To: P J P; +Cc: Markus Armbruster, Prasad J Pandit, Qemu Developers, Liu Ling
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
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