Re: [Qemu-devel] [PATCH] qdict: fix unbounded stack for qdict_array_entries

[Peter Xu <peterx@redhat.com>]

Sorry to forgot CCing Eric/Markus/Kevin.

This patch title is not correct, which should be:

"Fix unbounded stack warning for qdict_array_entries"

Do I need to re-send with the same content?

I'm using g_strdup_printf() here, considering it's most convenient,
safe, and as long as it's called rarely only when quorum device
opens.

Thanks.
Peter

On Wed, Mar 09, 2016 at 02:03:38PM +0800, Peter Xu wrote:
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
>  qobject/qdict.c | 15 ++++++---------
>  1 file changed, 6 insertions(+), 9 deletions(-)
> 
> diff --git a/qobject/qdict.c b/qobject/qdict.c
> index 9833bd0..9188a87 100644
> --- a/qobject/qdict.c
> +++ b/qobject/qdict.c
> @@ -704,19 +704,16 @@ int qdict_array_entries(QDict *src, const char *subqdict)
>      for (i = 0; i < INT_MAX; i++) {
>          QObject *subqobj;
>          int subqdict_entries;
> -        size_t slen = 32 + subqdict_len;
> -        char indexstr[slen], prefix[slen];
> -        size_t snprintf_ret;
> +        char *prefix = g_strdup_printf("%s%u.", subqdict, i);
>  
> -        snprintf_ret = snprintf(indexstr, slen, "%s%u", subqdict, i);
> -        assert(snprintf_ret < slen);
> +        subqdict_entries = qdict_count_prefixed_entries(src, prefix);
>  
> -        subqobj = qdict_get(src, indexstr);
> +        /* Remove ending "." */
> +        prefix[strlen(prefix) - 1] = 0x00;
> +        subqobj = qdict_get(src, prefix);
>  
> -        snprintf_ret = snprintf(prefix, slen, "%s%u.", subqdict, i);
> -        assert(snprintf_ret < slen);
> +        g_free(prefix);
>  
> -        subqdict_entries = qdict_count_prefixed_entries(src, prefix);
>          if (subqdict_entries < 0) {
>              return subqdict_entries;
>          }
> -- 
> 2.4.3
>