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liblzma: file info decoder: Add an integer overflow check

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After the previous commit, the overflow should be impossible, but it's
better to add the check anyway.

Fixes: https://github.com/tukaani-project/xz/pull/226
This commit is contained in:
Lasse Collin 2026-06-16 21:48:57 +03:00
parent a73f4c6715
commit 56c18ccfb7
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1 changed files with 7 additions and 0 deletions
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7
src/liblzma/common/file_info.c
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@ -717,6 +717,13 @@ file_info_decoder_memconfig(void *coder_ptr, uint64_t *memusage,
} }
} }
// combined_index_memusage + this_index_memusage shouldn't overflow
// because combined_index_memusage is limited by how much can be
// successfully allocated, and this_index_memusage is limited by
// INDEX_RECORDS_MAX in index_decoder.c. Check for overflow anyway.
if (UINT64_MAX - combined_index_memusage < this_index_memusage)
return LZMA_PROG_ERROR;
// Now we know the total memory usage/requirement. If we had neither // Now we know the total memory usage/requirement. If we had neither
// old Indexes nor a new Index, this will be zero which isn't // old Indexes nor a new Index, this will be zero which isn't
// acceptable as lzma_memusage() has to return non-zero on success // acceptable as lzma_memusage() has to return non-zero on success