[FFmpeg-devel] [PATCH] avcodec/zmbv: optimize motion compensation with memcpy()

[Tomas Härdin]

mån 2019-04-22 klockan 21:33 +0200 skrev Michael Niedermayer:
> Fixes: Timeout (16 sec - 7 sec)
> Fixes: 14237/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ZMBV_fuzzer-5693453897302016
> 
> 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/zmbv.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/libavcodec/zmbv.c b/libavcodec/zmbv.c
> index 898b62d065..99e735cfd9 100644
> --- a/libavcodec/zmbv.c
> +++ b/libavcodec/zmbv.c
> @@ -121,6 +121,8 @@ static int zmbv_decode_xor_8(ZmbvContext *c)
>              for (j = 0; j < bh2; j++) {
>                  if (my + j < 0 || my + j >= c->height) {
>                      memset(out, 0, bw2);
> +                } else if (mx >= 0 && mx + bw2 <= c->width){
> +                    memcpy(out, tprev, sizeof(*out) * bw2);
>                  } else {
>                      for (i = 0; i < bw2; i++) {
>                          if (mx + i < 0 || mx + i >= c->width)
> @@ -193,6 +195,8 @@ static int zmbv_decode_xor_16(ZmbvContext *c)
>              for (j = 0; j < bh2; j++) {
>                  if (my + j < 0 || my + j >= c->height) {
>                      memset(out, 0, bw2 * 2);
> +                } else if (mx >= 0 && mx + bw2 <= c->width){
> +                    memcpy(out, tprev, sizeof(*out) * bw2);
>                  } else {
>                      for (i = 0; i < bw2; i++) {
>                          if (mx + i < 0 || mx + i >= c->width)
> @@ -270,6 +274,8 @@ static int zmbv_decode_xor_24(ZmbvContext *c)
>              for (j = 0; j < bh2; j++) {
>                  if (my + j < 0 || my + j >= c->height) {
>                      memset(out, 0, bw2 * 3);
> +                } else if (mx >= 0 && mx + bw2 <= c->width){
> +                    memcpy(out, tprev, 3 * bw2);
>                  } else {
>                      for (i = 0; i < bw2; i++){
>                          if (mx + i < 0 || mx + i >= c->width) {
> @@ -351,6 +357,8 @@ static int zmbv_decode_xor_32(ZmbvContext *c)
>              for (j = 0; j < bh2; j++) {
>                  if (my + j < 0 || my + j >= c->height) {
>                      memset(out, 0, bw2 * 4);
> +                } else if (mx >= 0 && mx + bw2 <= c->width){
> +                    memcpy(out, tprev, sizeof(*out) * bw2);

Should be ok since out and tprev point to different areas in memory

/Tomas