netdev - Re: [PATCH iproute2] tc: u32: check return value from snprintf

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Message-ID: <ZcnHwRCr6s3T8VXt@Laptop-X1>
Date: Mon, 12 Feb 2024 15:24:49 +0800
From: Hangbin Liu <liuhangbin@...il.com>
To: Stephen Hemminger <stephen@...workplumber.org>
Cc: netdev@...r.kernel.org, jhs@...atatu.com
Subject: Re: [PATCH iproute2] tc: u32: check return value from snprintf

On Sat, Feb 10, 2024 at 05:04:23PM -0800, Stephen Hemminger wrote:
> Add assertion to check for case of snprintf failing (bad format?)
> or buffer getting full.
> 
> Signed-off-by: Stephen Hemminger <stephen@...workplumber.org>

Hi Stephen,

Is there a bug report or something else that we only do the assertion
for tc/f_u32.c?

Thanks
Hangbin

> ---
>  tc/f_u32.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/tc/f_u32.c b/tc/f_u32.c
> index 913ec1de435d..8a2413103906 100644
> --- a/tc/f_u32.c
> +++ b/tc/f_u32.c
> @@ -7,6 +7,7 @@
>   *
>   */
>  
> +#include <assert.h>
>  #include <stdio.h>
>  #include <stdlib.h>
>  #include <unistd.h>
> @@ -87,6 +88,7 @@ static char *sprint_u32_handle(__u32 handle, char *buf)
>  	if (htid) {
>  		int l = snprintf(b, bsize, "%x:", htid>>20);
>  
> +		assert(l > 0 && l < bsize);
>  		bsize -= l;
>  		b += l;
>  	}
> @@ -94,12 +96,14 @@ static char *sprint_u32_handle(__u32 handle, char *buf)
>  		if (hash) {
>  			int l = snprintf(b, bsize, "%x", hash);
>  
> +			assert(l > 0 && l < bsize);
>  			bsize -= l;
>  			b += l;
>  		}
>  		if (nodeid) {
>  			int l = snprintf(b, bsize, ":%x", nodeid);
>  
> +			assert(l > 0 && l < bsize);
>  			bsize -= l;
>  			b += l;
>  		}
> -- 
> 2.43.0
>