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[FFmpeg-devel,4/5] avformat/vividas: Check n_sb_blocks against input space

Message ID 20190904160458.28245-4-michael@niedermayer.cc
State Accepted
Commit 8e51f35f81c250892a97b6cf4b7c836ce7a3ffaf
Headers show

Commit Message

Michael Niedermayer Sept. 4, 2019, 4:04 p.m. UTC 
Fixes: OOM
Fixes: 16726/clusterfuzz-testcase-minimized-ffmpeg_DEMUXER_fuzzer-5719320750981120

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavformat/vividas.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)
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Patch

diff --git a/libavformat/vividas.c b/libavformat/vividas.c
index 645e322b6e..7ccec85761 100644
--- a/libavformat/vividas.c
+++ b/libavformat/vividas.c
@@ -420,7 +420,7 @@  static int track_header(VividasDemuxContext *viv, AVFormatContext *s,  uint8_t *
     return 0;
 }
 
-static void track_index(VividasDemuxContext *viv, AVFormatContext *s, uint8_t *buf, unsigned size)
+static int track_index(VividasDemuxContext *viv, AVFormatContext *s, uint8_t *buf, unsigned size)
 {
     int64_t off;
     int64_t poff;
@@ -430,16 +430,21 @@  static void track_index(VividasDemuxContext *viv, AVFormatContext *s, uint8_t *b
 
     pb = avio_alloc_context(buf, size, 0, NULL, NULL, NULL, NULL);
     if (!pb)
-        return;
+        return AVERROR(ENOMEM);
 
     ffio_read_varlen(pb); // track_index_len
     avio_r8(pb); // 'c'
     viv->n_sb_blocks = ffio_read_varlen(pb);
+    if (viv->n_sb_blocks * 2 > size) {
+        viv->n_sb_blocks = 0;
+        av_free(pb);
+        return AVERROR_INVALIDDATA;
+    }
     viv->sb_blocks = av_calloc(viv->n_sb_blocks, sizeof(VIV_SB_block));
     if (!viv->sb_blocks) {
         viv->n_sb_blocks = 0;
         av_free(pb);
-        return;
+        return AVERROR(ENOMEM);
     }
 
     off = 0;
@@ -462,6 +467,8 @@  static void track_index(VividasDemuxContext *viv, AVFormatContext *s, uint8_t *b
 
     viv->sb_entries = av_calloc(maxnp, sizeof(VIV_SB_entry));
     av_free(pb);
+
+    return 0;
 }
 
 static void load_sb_block(AVFormatContext *s, VividasDemuxContext *viv, unsigned expected_size)
@@ -587,8 +594,10 @@  static int viv_read_header(AVFormatContext *s)
     buf = read_vblock(pb, &v, key, &k2, v);
     if (!buf)
         return AVERROR(EIO);
-    track_index(viv, s, buf, v);
+    ret = track_index(viv, s, buf, v);
     av_free(buf);
+    if (ret < 0)
+        return ret;
 
     viv->sb_offset = avio_tell(pb);
     if (viv->n_sb_blocks > 0) {