Re: [dpdk-stable] [dpdk-dev] [PATCH v3] drivers: fix to replace strcat with strlcat

[Bruce Richardson <bruce.richardson@intel.com>]

On Wed, Feb 27, 2019 at 06:02:51AM +0000, Chaitanya Babu Talluri wrote:
> Strcat does not check the destination length and there might be
> chances of string overflow so instead of strcat, strlcat is used.
> 
> Fixes: 540a211084 ("bnx2x: driver core")
> Fixes: e163c18a15 ("net/i40e: update ptype and pctype info")
> Fixes: ef28aa96e5 ("net/nfp: support multiprocess")
> Fixes: 6f4eec2565 ("test/crypto: enhance scheduler unit tests")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Chaitanya Babu Talluri <tallurix.chaitanya.babu@intel.com>
> ---
> v3: Instead of strncat, used strlcat.
> v2: Instead of strncat, used snprintf.
> ---
>  drivers/net/bnx2x/bnx2x.c                  |  6 ++++--
>  drivers/net/i40e/i40e_ethdev.c             |  6 ++++--
>  drivers/net/nfp/nfpcore/nfp_cpp_pcie_ops.c | 10 ++++++----
>  test/test/test_cryptodev.c                 |  5 ++++-
>  4 files changed, 18 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/net/bnx2x/bnx2x.c b/drivers/net/bnx2x/bnx2x.c
> index 4c775c163..e418fd7d1 100644
> --- a/drivers/net/bnx2x/bnx2x.c
> +++ b/drivers/net/bnx2x/bnx2x.c
> @@ -11734,13 +11734,15 @@ static const char *get_bnx2x_flags(uint32_t flags)
>  
>  	for (i = 0; i < 5; i++)
>  		if (flags & (1 << i)) {
> -			strcat(flag_str, flag[i]);
> +			strlcat(flag_str, flag[i],
> +				BNX2X_INFO_STR_MAX - strlen(flag_str) - 1);
>  			flags ^= (1 << i);
>  		}
>  	if (flags) {
>  		static char unknown[BNX2X_INFO_STR_MAX];
>  		snprintf(unknown, 32, "Unknown flag mask %x", flags);
> -		strcat(flag_str, unknown);
> +		strlcat(flag_str, unknown,
> +			BNX2X_INFO_STR_MAX  - strlen(flag_str) - 1);
>  	}
This doesn't look right to me. "Strlcat" takes the saner approach of having
the length parameter being total length so subtraction etc. should not be
necessary. I think this should just be
"strlcat(flag_str, unknown, BNX2X_INFO_STR_MAX);"