libwebp: cherry-pick some demux changes

these make the demuxer more strict when parsing files with VP8X flags that
don't match the data.

e18e667 demux: strictly enforce the animation flag
61cb884 demux: (non-exp) fail if the fragmented flag is set

BUG=317284
R=urvang@google.com
TBR=fbarchard

Review URL: https://codereview.chromium.org/60863004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235867 0039d316-1c4b-4281-b951-d872f2087c98

third_party/libwebp/README.chromium

@@ -29,3 +29,5 @@ Cherry-picks:
   92d47e4 improve VP8L signature detection by checking the version bits too
   dde91fd Demux: Correct the extended format validation
   96ad0e0 VPLBitReader: Catch error if bit_pos > LBITS.
+  e18e667 demux: strictly enforce the animation flag
+  61cb884 demux: (non-exp) fail if the fragmented flag is set

third_party/libwebp/demux/demux.c

@@ -509,8 +509,9 @@ static ParseStatus ParseVP8X(WebPDemuxer* const dmux) {
       case MKFOURCC('A', 'L', 'P', 'H'):
       case MKFOURCC('V', 'P', '8', ' '):
       case MKFOURCC('V', 'P', '8', 'L'): {
+        const int has_frames = !!(dmux->feature_flags_ & ANIMATION_FLAG);
         // check that this isn't an animation (all frames should be in an ANMF).
-        if (anim_chunks > 0) return PARSE_ERROR;
+        if (anim_chunks > 0 || has_frames) return PARSE_ERROR;
 
         Rewind(mem, CHUNK_HEADER_SIZE);
         status = ParseSingleImage(dmux);
@@ -599,6 +600,8 @@ static int IsValidSimpleFormat(const WebPDemuxer* const dmux) {
 
 // If 'exact' is true, check that the image resolution matches the canvas.
 // If 'exact' is false, check that the x/y offsets do not exceed the canvas.
+// TODO(jzern): this is insufficient in the fragmented image case if the
+// expectation is that the fragments completely cover the canvas.
 static int CheckFrameBounds(const Frame* const frame, int exact,
                             int canvas_width, int canvas_height) {
   if (exact) {
@@ -626,6 +629,9 @@ static int IsValidExtendedFormat(const WebPDemuxer* const dmux) {
   if (dmux->canvas_width_ <= 0 || dmux->canvas_height_ <= 0) return 0;
   if (dmux->loop_count_ < 0) return 0;
   if (dmux->state_ == WEBP_DEMUX_DONE && dmux->frames_ == NULL) return 0;
+#ifndef WEBP_EXPERIMENTAL_FEATURES
+  if (has_fragments) return 0;
+#endif
 
   while (f != NULL) {
     const int cur_frame_set = f->frame_num_;
@@ -637,8 +643,10 @@ static int IsValidExtendedFormat(const WebPDemuxer* const dmux) {
       const ChunkData* const image = f->img_components_;
       const ChunkData* const alpha = f->img_components_ + 1;
 
+      if (has_fragments && !f->is_fragment_) return 0;
       if (!has_fragments && f->is_fragment_) return 0;
       if (!has_frames && f->frame_num_ > 1) return 0;
+
       if (f->complete_) {
         if (alpha->size_ == 0 && image->size_ == 0) return 0;
         // Ensure alpha precedes image bitstream.