[FFmpeg-cvslog] avcodec/dfpwmdec: Check packet size more completely

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Thu Mar 17 22:52:52 2022 +0100| [b59ea948cdcb8422964595c32076312756550f17] | committer: Michael Niedermayer

avcodec/dfpwmdec: Check packet size more completely

Fixes: out of array access
Fixes: 45497/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_DFPWM_fuzzer-5239786212818944.fuzz
Fixes: 45510/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_DFPWM_fuzzer-4947856883056640

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Reviewed-by: Paul B Mahol <onemda at gmail.com>
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=b59ea948cdcb8422964595c32076312756550f17
---

 libavcodec/dfpwmdec.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/libavcodec/dfpwmdec.c b/libavcodec/dfpwmdec.c
index 27b60a4ea4..e11f393ee4 100644
--- a/libavcodec/dfpwmdec.c
+++ b/libavcodec/dfpwmdec.c
@@ -106,7 +106,10 @@ static int dfpwm_dec_frame(struct AVCodecContext *ctx, void *data,
     AVFrame *frame = data;
     int ret;
 
-    frame->nb_samples = packet->size * 8 / ctx->ch_layout.nb_channels;
+    if (packet->size * 8LL % ctx->ch_layout.nb_channels)
+        return AVERROR_PATCHWELCOME;
+
+    frame->nb_samples = packet->size * 8LL / ctx->ch_layout.nb_channels;
     if (frame->nb_samples <= 0) {
         av_log(ctx, AV_LOG_ERROR, "invalid number of samples in packet\n");
         return AVERROR_INVALIDDATA;