49 lines
2.0 KiB
Diff
49 lines
2.0 KiB
Diff
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From 95ea5226c870449522240ccff26f0b006037c520 Mon Sep 17 00:00:00 2001
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From: Vincent Rabaud <vrabaud@google.com>
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Date: Mon, 11 Sep 2023 16:06:08 +0200
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Subject: [PATCH] Fix invalid incremental decoding check.
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The first condition is only necessary if we have not read enough
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(enough being defined by src_last, not src_end which is the end
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of the image).
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The second condition now fits the comment below: "if not
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incremental, and we are past the end of buffer".
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BUG=oss-fuzz:62136
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Change-Id: I0700f67c62db8e1c02c2e429a069a71e606a5e4f
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---
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src/dec/vp8l_dec.c | 15 +++++++++++++--
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1 file changed, 13 insertions(+), 2 deletions(-)
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diff --git a/src/dec/vp8l_dec.c b/src/dec/vp8l_dec.c
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index 5ab34f56..809b1aa9 100644
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--- a/src/dec/vp8l_dec.c
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+++ b/src/dec/vp8l_dec.c
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@@ -1233,9 +1233,20 @@ static int DecodeImageData(VP8LDecoder* const dec, uint32_t* const data,
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}
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br->eos_ = VP8LIsEndOfStream(br);
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- if (dec->incremental_ && br->eos_ && src < src_end) {
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+ // In incremental decoding:
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+ // br->eos_ && src < src_last: if 'br' reached the end of the buffer and
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+ // 'src_last' has not been reached yet, there is not enough data. 'dec' has to
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+ // be reset until there is more data.
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+ // !br->eos_ && src < src_last: this cannot happen as either the buffer is
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+ // fully read, either enough has been read to reach 'src_last'.
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+ // src >= src_last: 'src_last' is reached, all is fine. 'src' can actually go
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+ // beyond 'src_last' in case the image is cropped and an LZ77 goes further.
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+ // The buffer might have been enough or there is some left. 'br->eos_' does
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+ // not matter.
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+ assert(!dec->incremental_ || (br->eos_ && src < src_last) || src >= src_last);
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+ if (dec->incremental_ && br->eos_ && src < src_last) {
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RestoreState(dec);
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- } else if (!br->eos_) {
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+ } else if ((dec->incremental_ && src >= src_last) || !br->eos_) {
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// Process the remaining rows corresponding to last row-block.
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if (process_func != NULL) {
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process_func(dec, row > last_row ? last_row : row);
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--
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2.41.0
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