Re: [B.A.T.M.A.N.] [PATCH] alfred: Avoid buffer overflow while querying ARP cache

[Antonio Quartulli <a@unstable.cc>]

[-- Attachment #1: Type: text/plain, Size: 1113 bytes --]

On Fri, Jan 27, 2017 at 03:10:44PM +0100, Sven Eckelmann wrote:
> The arpreq.arp_dev is a limited buffer (16 bytes). Avoid that more bytes
> from the interface name are copied into this buffer by switching from
> strcpy to strncpy.
> 
> Fixes: c7da798113a2 ("alfred: IPv4 multicast distribution support.")
> Signed-off-by: Sven Eckelmann <sven@narfation.org>
> ---
>  util.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/util.c b/util.c
> index 84ab3af..ed83895 100644
> --- a/util.c
> +++ b/util.c
> @@ -92,7 +92,9 @@ int ipv4_arp_request(struct interface *interface, const alfred_addr *addr,
>  	sin->sin_family = AF_INET;
>  	sin->sin_addr.s_addr = addr->ipv4.s_addr;
>  
> -	strcpy(arpreq.arp_dev, interface->interface);
> +	strncpy(arpreq.arp_dev, interface->interface, sizeof(arpreq.arp_dev));

arpreq is already set to 0 few lines above. why not simpling
"sizeof(arpreq.arp_dev) - 1" as last argument for the strncpy() and avoid the
line below?

Or is this required for consistency with the rest of the code?


Cheers,

-- 
Antonio Quartulli

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 801 bytes --]