[Mesa-dev] [PATCH] util/build-id: check dlpi_name before strstr call

[Emil Velikov]

On 16 March 2017 at 06:10, Tapani Pälli <tapani.palli at intel.com> wrote:
> According to dl_iterate_phdr man page first object visited is the
> main program where dlpi_name is an empty string. This fixes segfault
> on Android when using build-id as identifier.
>
> Signed-off-by: Tapani Pälli <tapani.palli at intel.com>
> ---
>  src/util/build_id.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/src/util/build_id.c b/src/util/build_id.c
> index c53e71d..797ea22 100644
> --- a/src/util/build_id.c
> +++ b/src/util/build_id.c
> @@ -55,6 +55,12 @@ build_id_find_nhdr_callback(struct dl_phdr_info *info, size_t size, void *data_)
>  {
>     struct callback_data *data = data_;
>
> +   /* The first object visited by callback is the main program.
> +    * For the main program, the dlpi_name field will be an empty string.
> +    */
> +   if (info->dlpi_name == NULL)
> +      return 0;
> +
>     char *ptr = strstr(info->dlpi_name, data->filename);
Current behaviour was OK on Linux platforms since Glibc (some versions
at least) provide a non-NULL empty string, which would not crash in
the strstr below.

That said, the fix the the correct thing to do and is

Fixes: d4fa083e11f ("util: Add utility build-id code.")
Reviewed-by: Emil Velikov <emil.velikov at collabora.com>

-Emil