[PATCH v2] net: fix checksum verification

[PATCH v2] net: fix checksum verification

[Baruch Siach]

Checksum calculation on data including its own checksum (as is the case with
IP headers) should give 0xffff before bit flipping. Current code works well
for the correct checksum case, but fails to identify errors.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
---
Untested.

v2: net_checksum() doesn't flip bits. Fix accordingly.

 net/net.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/net.c b/net/net.c
index 0bd9084..058a4d3 100644
--- a/net/net.c
+++ b/net/net.c
@@ -41,7 +41,7 @@ static unsigned int net_ip_id;
 
 int net_checksum_ok(unsigned char *ptr, int len)
 {
-	return net_checksum(ptr, len) + 1;
+	return net_checksum(ptr, len) == 0xffff;
 }
 
 uint16_t net_checksum(unsigned char *ptr, int len)
-- 
1.8.4.rc1


_______________________________________________
barebox mailing list
barebox@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/barebox

Re: [PATCH v2] net: fix checksum verification

[Sascha Hauer]

On Sun, Aug 11, 2013 at 07:35:45AM +0300, Baruch Siach wrote:
> Checksum calculation on data including its own checksum (as is the case with
> IP headers) should give 0xffff before bit flipping. Current code works well
> for the correct checksum case, but fails to identify errors.
> 
> Signed-off-by: Baruch Siach <baruch@tkos.co.il>

Applied, thanks

Sascha

> ---
> Untested.
> 
> v2: net_checksum() doesn't flip bits. Fix accordingly.
> 
>  net/net.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/net.c b/net/net.c
> index 0bd9084..058a4d3 100644
> --- a/net/net.c
> +++ b/net/net.c
> @@ -41,7 +41,7 @@ static unsigned int net_ip_id;
>  
>  int net_checksum_ok(unsigned char *ptr, int len)
>  {
> -	return net_checksum(ptr, len) + 1;
> +	return net_checksum(ptr, len) == 0xffff;
>  }
>  
>  uint16_t net_checksum(unsigned char *ptr, int len)
> -- 
> 1.8.4.rc1
> 
> 
> _______________________________________________
> barebox mailing list
> barebox@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/barebox
> 

-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

_______________________________________________
barebox mailing list
barebox@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/barebox