avformat/mlvdec: fix size checks

michaelni · michaelni · commit 2e7364727caa · 2025-02-26T01:26:32.000+01:00
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> (cherry picked from commit 251d43a) Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
diff --git a/libavformat/mlvdec.c b/libavformat/mlvdec.c
@@ -437,19 +437,25 @@ static int read_packet(AVFormatContext *avctx, AVPacket *pkt)
     if (size < 16)
         return AVERROR_INVALIDDATA;
     avio_skip(pb, 12); //timestamp, frameNumber
-    if (st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO)
+    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;
 
     if ((mlv->class[st->id] & (MLV_CLASS_FLAG_DELTA|MLV_CLASS_FLAG_LZMA))) {
         ret = AVERROR_PATCHWELCOME;
     } else if (st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
         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)
