avcodec/iff: Over-allocate ham_palbuf for HAM6 IFF-PBM
authorMichael Niedermayer <michael@niedermayer.cc>
Fri, 3 Jan 2020 22:24:15 +0000 (23:24 +0100)
committerMichael Niedermayer <michael@niedermayer.cc>
Thu, 30 Jan 2020 18:56:25 +0000 (19:56 +0100)
IFF-PBM-HAM6 can read out of array without this overallocation
Fixes: Out of array read
Fixes: 19752/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_IFF_ILBM_fuzzer-5675331403120640

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
libavcodec/iff.c

index d826e78..acd6519 100644 (file)
@@ -332,13 +332,17 @@ static int extract_header(AVCodecContext *const avctx,
             int i, count = FFMIN(palette_size / 3, 1 << s->ham);
             int ham_count;
             const uint8_t *const palette = avctx->extradata + AV_RB16(avctx->extradata);
+            int extra_space = 1;
+
+            if (avctx->codec_tag == MKTAG('P', 'B', 'M', ' ') && s->ham == 4)
+                extra_space = 4;
 
             s->ham_buf = av_malloc((s->planesize * 8) + AV_INPUT_BUFFER_PADDING_SIZE);
             if (!s->ham_buf)
                 return AVERROR(ENOMEM);
 
             ham_count = 8 * (1 << s->ham);
-            s->ham_palbuf = av_malloc((ham_count << !!(s->masking == MASK_HAS_MASK)) * sizeof (uint32_t) + AV_INPUT_BUFFER_PADDING_SIZE);
+            s->ham_palbuf = av_malloc(extra_space * (ham_count << !!(s->masking == MASK_HAS_MASK)) * sizeof (uint32_t) + AV_INPUT_BUFFER_PADDING_SIZE);
             if (!s->ham_palbuf) {
                 av_freep(&s->ham_buf);
                 return AVERROR(ENOMEM);