read: add bounds checks during extent merge to prevent buffer overflow#3004
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Naveed8951 wants to merge 2 commits intoAOMediaCodec:mainfrom
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read: add bounds checks during extent merge to prevent buffer overflow#3004Naveed8951 wants to merge 2 commits intoAOMediaCodec:mainfrom
Naveed8951 wants to merge 2 commits intoAOMediaCodec:mainfrom
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Validate write offsets and per-extent copy sizes before memcpy when merging item extents to avoid out-of-bounds writes triggered by malformed or malicious AVIF metadata. Reject invalid extents with AVIF_RESULT_BMFF_PARSE_FAILED.
wantehchang
reviewed
Feb 6, 2026
src/read.c
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| AVIF_ASSERT_OR_RETURN(front); | ||
| // Validate that the write will not exceed the allocated buffer | ||
| if ((size_t)(front - item->mergedExtents.data) > item->mergedExtents.size || | ||
| bytesToRead > item->mergedExtents.size - (size_t)(front - item->mergedExtents.data)) { |
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At this point we have already validated all the sizes and offsets. These two conditions cannot be true if our code is correct. So this check is an assertion. We can consider adding this assertion because the code is quite complicated, but the error code should be AVIF_RESULT_INTERNAL_ERROR, not AVIF_RESULT_BMFF_PARSE_FAILED.
The expression (size_t)(front - item->mergedExtents.data) occurs three times. I suggest saving the result of this expression in a local variable to simplify the code.
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Updated to return AVIF_RESULT_INTERNAL_ERROR and stored the write offset in a local variable as suggested. |
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Validate write offsets and per-extent copy sizes before memcpy when merging item extents to avoid out-of-bounds writes triggered by malformed or malicious AVIF metadata.
Reject invalid extents with AVIF_RESULT_BMFF_PARSE_FAILED.