Subject: Re: [patch v2] bridge: make buffer larger in br_setlink()

From: walter harms <[email-masked]>
Date: Fri, 07 Dec 2012 17:07:24 +0100

Am 07.12.2012 12:10, schrieb Dan Carpenter:
> We pass IFLA_BRPORT_MAX to nla_parse_nested() so we need
> IFLA_BRPORT_MAX + 1 elements.  Also Smatch complains that we read past
> the end of the array when in br_set_port_flag() when it's called with
> IFLA_BRPORT_FAST_LEAVE.
> 

I have no clue why nla_parse_nested() need IFLA_BRPORT_MAX elements.
but the majory of loop look like
for(i=0;i<max;++)
most programmers will think this way.
So it seems the place to fix is nla_parse_nested().
doing not so is asking for trouble (in the long run).
At least this function needs a big warning label that (max-1)
is actually needed.

just my two cents,
 wh

> Signed-off-by: Dan Carpenter <[email-masked]>
> ---
> v2: Style tweak.
> 
> Only needed in linux-next.
> 
> diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
> index 850b7d1..cfc5cfe 100644
> --- a/net/bridge/br_netlink.c
> +++ b/net/bridge/br_netlink.c
> @@ -239,7 +239,7 @@ int br_setlink(struct net_device *dev, struct nlmsghdr *nlh)
>  	struct ifinfomsg *ifm;
>  	struct nlattr *protinfo;
>  	struct net_bridge_port *p;
> -	struct nlattr *tb[IFLA_BRPORT_MAX];
> +	struct nlattr *tb[IFLA_BRPORT_MAX + 1];
>  	int err;
>  
>  	ifm = nlmsg_data(nlh);
> 
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