Re: [dpdk-dev] [PATCH] kvargs: fix a heap-buffer-overflow when detect list

[Olivier Matz <olivier.matz@6wind.com>]

Hi,

On Thu, Mar 19, 2020 at 12:38:00PM +0800, wangyunjian wrote:
> From: Yunjian Wang <wangyunjian@huawei.com>
> 
> When an input params'value is '[', leading to the 'str' over read
> or heap-buffer-overflow. So we can check the 'ctx1' length to avoid
> this problem.
> 
> Fixes: cc0579f2339a ("kvargs: support list value")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Yunjian Wang <wangyunjian@huawei.com>
> ---
>  lib/librte_kvargs/rte_kvargs.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/librte_kvargs/rte_kvargs.c b/lib/librte_kvargs/rte_kvargs.c
> index d39332999..a1144b90b 100644
> --- a/lib/librte_kvargs/rte_kvargs.c
> +++ b/lib/librte_kvargs/rte_kvargs.c
> @@ -48,7 +48,8 @@ rte_kvargs_tokenize(struct rte_kvargs *kvlist, const char *params)
>  		str = kvlist->pairs[i].value;
>  		if (str[0] == '[') {
>  			/* Find the end of the list. */
> -			while (str[strlen(str) - 1] != ']') {
> +			while ((str[strlen(str) - 1] != ']') &&
> +			       (strlen(ctx1) > 0)) {
>  				/* Restore the comma erased by strtok_r(). */
>  				str[strlen(str)] = ',';
>  				/* Parse until next comma. */

I would prefer to keep the while condition as is, like this:

                                /* Restore the comma erased by strtok_r(). */
+                               if (ctx1[0] == '\0')
+                                       return -1; /* no closing bracket */
                                str[strlen(str)] = ',';

It avoids an uneeded call to strlen(), and ensure we are returning
an error in that case.

I also wanted to add a test case, but I realized that kvargs unit tests
are broken now. I have done 2 patches to fix them.

Do you mind if I send a patchset with these 2 patches + your patch
(keeping your signed-off and doing the modification described above),
to ensure there is no implicit dependency?

Thanks,
Olivier