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webpmux: tolerate false positive Alpha flag

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Change-Id: I390aebdda31f5320e83b7d7012735947a234650b
This commit is contained in:
hui su 2017-05-19 11:26:37 -07:00
parent dd7e83cca7
commit 972104b34b
2 changed files with 18 additions and 2 deletions
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17
src/mux/muxinternal.c
View File

@ -504,6 +504,20 @@ WebPMuxError MuxValidate(const WebPMux* const mux) {
if (!has_animation && (num_anim == 1 || num_frames > 0)) {
return WEBP_MUX_INVALID_ARGUMENT;
}
if (!has_animation) {
const WebPMuxImage* images = mux->images_;
// There can be only one image.
if (images == NULL || images->next_ != NULL) {
return WEBP_MUX_INVALID_ARGUMENT;
}
// Size must match.
if (mux->canvas_width_ > 0) {
if (images->width_ != mux->canvas_width_ ||
images->height_ != mux->canvas_height_) {
return WEBP_MUX_INVALID_ARGUMENT;
}
}
}
}
// Verify either VP8X chunk is present OR there is only one elem in
@ -515,6 +529,7 @@ WebPMuxError MuxValidate(const WebPMux* const mux) {
if (num_vp8x == 0 && num_images != 1) return WEBP_MUX_INVALID_ARGUMENT;
// ALPHA_FLAG & alpha chunk(s) are consistent.
// Note: ALPHA_FLAG can be set when there is actually no Alpha data present.
if (MuxHasAlpha(mux->images_)) {
if (num_vp8x > 0) {
// VP8X chunk is present, so it should contain ALPHA_FLAG.
@ -525,8 +540,6 @@ WebPMuxError MuxValidate(const WebPMux* const mux) {
if (err != WEBP_MUX_OK) return err;
if (num_alpha > 0) return WEBP_MUX_INVALID_ARGUMENT;
}
} else { // Mux doesn't need alpha. So, ALPHA_FLAG should NOT be present.
if (flags & ALPHA_FLAG) return WEBP_MUX_INVALID_ARGUMENT;
}
return WEBP_MUX_OK;

3
src/mux/muxread.c
View File

@ -270,6 +270,9 @@ WebPMux* WebPMuxCreateInternal(const WebPData* bitstream, int copy_data,
ChunkInit(&chunk);
}
// Incomplete image.
if (wpi->is_partial_) goto Err;
// Validate mux if complete.
if (MuxValidate(mux) != WEBP_MUX_OK) goto Err;