[FFmpeg-devel] [PATCH] avcodec/elsdec: Fix memleaks

[James Almer]

On 4/24/2018 9:58 PM, Michael Niedermayer wrote:
> Fixes: 6798/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_G2M_fuzzer-5135899701542912
> 
> Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> ---
>  libavcodec/elsdec.c | 10 ++++++----
>  libavcodec/g2meet.c |  1 +
>  2 files changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/libavcodec/elsdec.c b/libavcodec/elsdec.c
> index 4797965457..8327662b4b 100644
> --- a/libavcodec/elsdec.c
> +++ b/libavcodec/elsdec.c
> @@ -271,7 +271,7 @@ void ff_els_decoder_init(ElsDecCtx *ctx, const uint8_t *in, size_t data_size)
>  
>  void ff_els_decoder_uninit(ElsUnsignedRung *rung)
>  {
> -    av_free(rung->rem_rung_list);
> +    av_freep(&rung->rem_rung_list);
>  }
>  
>  static int els_import_byte(ElsDecCtx *ctx)
> @@ -389,16 +389,18 @@ unsigned ff_els_decode_unsigned(ElsDecCtx *ctx, ElsUnsignedRung *ur)
>          else {
>              if (!rung_node->next_index) {
>                  if (ur->rung_list_size <= (ur->avail_index + 2) * sizeof(ElsRungNode)) {
> +                    void *ptr_tmp;
>                      // remember rung_node position
>                      ptrdiff_t pos     = rung_node - ur->rem_rung_list;
> -                    ur->rem_rung_list = av_realloc(ur->rem_rung_list,
> +                    ptr_tmp = av_realloc(ur->rem_rung_list,
>                                                     ur->rung_list_size +
>                                                     RUNG_SPACE);

Use av_reallocp instead, to remove the tmp pointer and the av_freep call
below.

> -                    if (!ur->rem_rung_list) {
> -                        av_free(ur->rem_rung_list);
> +                    if (!ptr_tmp) {
> +                        av_freep(&ur->rem_rung_list);
>                          ctx->err = AVERROR(ENOMEM);
>                          return 0;
>                      }
> +                    ur->rem_rung_list = ptr_tmp;
>                      memset((uint8_t *) ur->rem_rung_list + ur->rung_list_size, 0,
>                             RUNG_SPACE);
>                      ur->rung_list_size += RUNG_SPACE;
> diff --git a/libavcodec/g2meet.c b/libavcodec/g2meet.c
> index a46157218f..b409dae813 100644
> --- a/libavcodec/g2meet.c
> +++ b/libavcodec/g2meet.c
> @@ -927,6 +927,7 @@ static int epic_jb_decode_tile(G2MContext *c, int tile_x, int tile_y,
>          if (c->ec.els_ctx.err != 0) {
>              av_log(avctx, AV_LOG_ERROR,
>                     "ePIC: couldn't decode transparency pixel!\n");
> +            ff_els_decoder_uninit(&c->ec.unsigned_rung);
>              return AVERROR_INVALIDDATA;
>          }
>  
>