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LibGfx: Add some chunk validation to decode_webp_extended()

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Nico Weber 2023-02-25 20:22:01 -05:00 • committed by Linus Groh
parent 9864963a08
commit 0393a37843
1 changed files with 33 additions and 0 deletions
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33
Userland/Libraries/LibGfx/WebPLoader.cpp
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@ -336,6 +336,8 @@ static ErrorOr<VP8XHeader> decode_webp_chunk_VP8X(WebPLoadingContext& context, C
// https://developers.google.com/speed/webp/docs/riff_container#extended_file_format
static ErrorOr<void> decode_webp_extended(WebPLoadingContext& context, ReadonlyBytes chunks)
{
VERIFY(context.first_chunk->type == FourCC("VP8X"));
// FIXME: This isn't quite to spec, which says
// "All chunks SHOULD be placed in the same order as listed above.
// If a chunk appears in the wrong place, the file is invalid, but readers MAY parse the file, ignoring the chunks that are out of order."
@ -362,6 +364,37 @@ static ErrorOr<void> decode_webp_extended(WebPLoadingContext& context, ReadonlyB
store(context.image_data_chunk, chunk);
}
// Validate chunks.
// https://developers.google.com/speed/webp/docs/riff_container#animation
// "ANIM Chunk: [...] This chunk MUST appear if the Animation flag in the VP8X chunk is set. If the Animation flag is not set and this chunk is present, it MUST be ignored."
if (context.vp8x_header.has_animation && !context.animation_header_chunk.has_value())
return context.error("WebPImageDecoderPlugin: Header claims animation, but no ANIM chunk");
if (!context.vp8x_header.has_animation && context.animation_header_chunk.has_value()) {
dbgln_if(WEBP_DEBUG, "WebPImageDecoderPlugin: Header claims no animation, but ANIM chunk present. Ignoring ANIM chunk.");
context.animation_header_chunk.clear();
}
// "ANMF Chunk: [...] If the Animation flag is not set, then this chunk SHOULD NOT be present."
if (!context.vp8x_header.has_animation && context.animation_header_chunk.has_value()) {
dbgln_if(WEBP_DEBUG, "WebPImageDecoderPlugin: Header claims no animation, but ANMF chunks present. Ignoring ANMF chunks.");
context.animation_frame_chunks.clear();
}
// https://developers.google.com/speed/webp/docs/riff_container#alpha
// "A frame containing a 'VP8L' chunk SHOULD NOT contain this chunk."
// FIXME: Also check in ANMF chunks.
if (context.alpha_chunk.has_value() && context.image_data_chunk.has_value() && context.image_data_chunk->type == FourCC("VP8L")) {
dbgln_if(WEBP_DEBUG, "WebPImageDecoderPlugin: VP8L frames should not have ALPH chunks. Ignoring ALPH chunk.");
context.alpha_chunk.clear();
}
// https://developers.google.com/speed/webp/docs/riff_container#color_profile
// "This chunk MUST appear before the image data."
// FIXME: Doesn't check animated files.
if (context.iccp_chunk.has_value() && context.image_data_chunk.has_value() && context.iccp_chunk->data.data() > context.image_data_chunk->data.data())
return context.error("WebPImageDecoderPlugin: ICCP chunk is after image data");
context.state = WebPLoadingContext::State::ChunksDecoded;
return {};
}