[FFmpeg-devel] [PATCH 2/2] avformat/mlvdec: fix size checks

[Michael Niedermayer <michael@niedermayer.cc>]

Fixes: heap-buffer-overflow
Fixes: 391962476/clusterfuzz-testcase-minimized-ffmpeg_dem_MLV_fuzzer-5746746587676672

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavformat/mlvdec.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/libavformat/mlvdec.c b/libavformat/mlvdec.c
index 6f4fa80f32b..44f5c207559 100644
--- a/libavformat/mlvdec.c
+++ b/libavformat/mlvdec.c
@@ -471,6 +471,9 @@ static int get_packet_lj92(AVFormatContext *avctx, AVStream *st, AVIOContext *pb
     uint8_t *stripofs, *matrixofs;
 
 #define MAX_HEADER_SIZE 2048
+    if ((uint64_t)size > INT32_MAX - MAX_HEADER_SIZE)
+        return AVERROR_PATCHWELCOME;
+
     if ((ret = av_new_packet(pkt, size + MAX_HEADER_SIZE)) < 0)
         return ret;
 
@@ -562,10 +565,14 @@ static int read_packet(AVFormatContext *avctx, AVPacket *pkt)
     avio_skip(pb, 12); //timestamp, frameNumber
     size -= 12;
     if (st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
+        if (size < 8)
+            return AVERROR_INVALIDDATA;
         avio_skip(pb, 8); // cropPosX, cropPosY, panPosX, panPosY
         size -= 8;
     }
     space = avio_rl32(pb);
+    if (size < space + 4LL)
+        return AVERROR_INVALIDDATA;
     avio_skip(pb, space);
     size -= space;
 
@@ -577,9 +584,7 @@ static int read_packet(AVFormatContext *avctx, AVPacket *pkt)
         else
             ret = av_get_packet(pb, pkt, (st->codecpar->width * st->codecpar->height * st->codecpar->bits_per_coded_sample + 7) >> 3);
     } else { // AVMEDIA_TYPE_AUDIO
-        if (space > UINT_MAX - 24 || size < (24 + space))
-            return AVERROR_INVALIDDATA;
-        ret = av_get_packet(pb, pkt, size - (24 + space));
+        ret = av_get_packet(pb, pkt, size - 4);
     }
 
     if (ret < 0)
-- 
2.48.1

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