[FFmpeg-devel] avcodec/mss4: Check input size against skip bits

Submitted by Michael Niedermayer on May 14, 2019, 12:50 p.m.

Details

Message ID 20190514125048.16746-1-michael@niedermayer.cc
State Accepted
Commit 0fef412dffb74fef3494f7fae0c138c32a444484
Headers show

Commit Message

Michael Niedermayer May 14, 2019, 12:50 p.m.
Fixes: Timeout (17sec -> 20ms)
Fixes: 14615/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MTS2_fuzzer-5093007763701760

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavcodec/mss4.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

Comments

Michael Niedermayer June 5, 2019, 11:08 a.m.
On Tue, May 14, 2019 at 02:50:48PM +0200, Michael Niedermayer wrote:
> Fixes: Timeout (17sec -> 20ms)
> Fixes: 14615/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MTS2_fuzzer-5093007763701760
> 
> Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> ---
>  libavcodec/mss4.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)

will apply

[...]

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diff --git a/libavcodec/mss4.c b/libavcodec/mss4.c
index b58c21be93..76c746a2d5 100644
--- a/libavcodec/mss4.c
+++ b/libavcodec/mss4.c
@@ -552,6 +552,11 @@  static int mss4_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
                "Empty frame found but it is not a skip frame.\n");
         return AVERROR_INVALIDDATA;
     }
+    mb_width  = FFALIGN(width,  16) >> 4;
+    mb_height = FFALIGN(height, 16) >> 4;
+
+    if (frame_type != SKIP_FRAME && 8*buf_size < 8*HEADER_SIZE + mb_width*mb_height)
+        return AVERROR_INVALIDDATA;
 
     if ((ret = ff_reget_buffer(avctx, c->pic)) < 0)
         return ret;
@@ -574,9 +579,6 @@  static int mss4_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
 
     if ((ret = init_get_bits8(&gb, buf + HEADER_SIZE, buf_size - HEADER_SIZE)) < 0)
         return ret;
-
-    mb_width  = FFALIGN(width,  16) >> 4;
-    mb_height = FFALIGN(height, 16) >> 4;
     dst[0] = c->pic->data[0];
     dst[1] = c->pic->data[1];
     dst[2] = c->pic->data[2];