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muxread,CreateInternal: fix riff size checks

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previously when adjusting size down based on a smaller riff_size the
checks were insufficient to prevent 'size -= RIFF_HEADER_SIZE' from
rolling over causing ChunkVerifyAndAssign to over read. the new checks
are imported from demux.c.

BUG=webp:386

Change-Id: If863c4a9892977b9ade7dd894392a0ecae13775c
This commit is contained in:
James Zern 2018-06-14 00:03:34 -07:00
parent 569001f19f
commit 2c70ad76c9
1 changed files with 6 additions and 9 deletions
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15
src/mux/muxread.c
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@ -187,7 +187,7 @@ WebPMux* WebPMuxCreateInternal(const WebPData* bitstream, int copy_data,
size = bitstream->size;
if (data == NULL) return NULL;
if (size < RIFF_HEADER_SIZE) return NULL;
if (size < RIFF_HEADER_SIZE + CHUNK_HEADER_SIZE) return NULL;
if (GetLE32(data + 0) != MKFOURCC('R', 'I', 'F', 'F') ||
GetLE32(data + CHUNK_HEADER_SIZE) != MKFOURCC('W', 'E', 'B', 'P')) {
return NULL;
@ -196,8 +196,6 @@ WebPMux* WebPMuxCreateInternal(const WebPData* bitstream, int copy_data,
mux = WebPMuxNew();
if (mux == NULL) return NULL;
if (size < RIFF_HEADER_SIZE + TAG_SIZE) goto Err;
tag = GetLE32(data + RIFF_HEADER_SIZE);
if (tag != kChunks[IDX_VP8].tag &&
tag != kChunks[IDX_VP8L].tag &&
@ -206,12 +204,11 @@ WebPMux* WebPMuxCreateInternal(const WebPData* bitstream, int copy_data,
}
riff_size = SizeWithPadding(GetLE32(data + TAG_SIZE));
if (riff_size > MAX_CHUNK_PAYLOAD || riff_size > size) {
goto Err;
} else {
if (riff_size < size) { // Redundant data after last chunk.
size = riff_size; // To make sure we don't read any data beyond mux_size.
}
if (riff_size < CHUNK_HEADER_SIZE) goto Err;
if (riff_size > MAX_CHUNK_PAYLOAD || riff_size > size) goto Err;
// There's no point in reading past the end of the RIFF chunk.
if (size > riff_size + CHUNK_HEADER_SIZE) {
size = riff_size + CHUNK_HEADER_SIZE;
}
end = data + size;