netdev - RE: [iproute PATCH v2 4/5] tc/tc_filter: Make sure filter name is not empty

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Date:   Fri, 18 Aug 2017 09:30:35 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Phil Sutter' <phil@....cc>,
        Stephen Hemminger <stephen@...workplumber.org>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: RE: [iproute PATCH v2 4/5] tc/tc_filter: Make sure filter name is
 not empty

From: Phil Sutter
> Sent: 17 August 2017 18:10
> The later check for 'k[0] != 0' requires a non-empty filter name,
> otherwise NULL pointer dereference in 'q' might happen.
> 
> Signed-off-by: Phil Sutter <phil@....cc>
> ---
>  tc/tc_filter.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/tc/tc_filter.c b/tc/tc_filter.c
> index b13fb9185d4fd..a799edb35886d 100644
> --- a/tc/tc_filter.c
> +++ b/tc/tc_filter.c
> @@ -412,6 +412,9 @@ static int tc_filter_get(int cmd, unsigned int flags, int argc, char **argv)
>  			usage();
>  			return 0;
>  		} else {
> +			if (!strlen(*argv))
> +				invarg("invalid filter name", *argv);

That is nearly as bad as:
	p[strlen(p)] = 0;

> +
>  			strncpy(k, *argv, sizeof(k)-1);
> 
>  			q = get_filter_kind(k);
> --
> 2.13.1