Implement overflow check in MaxCompressedLength function#242
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yusmer96-maker wants to merge 3 commits into
Open
Implement overflow check in MaxCompressedLength function#242yusmer96-maker wants to merge 3 commits into
yusmer96-maker wants to merge 3 commits into
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Add overflow check for buffer allocation in MaxCompressedLength
danilak-G
reviewed
Jun 4, 2026
| size_t MaxCompressedLength(size_t source_bytes) { | ||
| // Avoid integer overflow that could cause undersized buffer allocations. | ||
| // Return SIZE_MAX to force a controlled allocation failure. | ||
| if (source_bytes > (SIZE_MAX - 32) / 7 * 6) { |
Collaborator
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LGTM. Can you use std::numeric_limits<size_t>::max() ?
Author
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Sure! I initially used SIZE_MAX because I didn't notice was included transitively through snappy-stubs-internal.h. Now that I see it's available, I'll update to std::numeric_limits<size_t>::max(). Thanks for the suggestion.
Updated the overflow check to use std::numeric_limits<size_t>::max() for clarity.
danilak-G
reviewed
Jun 4, 2026
| #include <cstdint> | ||
| #include <cstdio> | ||
| #include <cstring> | ||
| #include <memory> |
Collaborator
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Let's have #include <limits> here as well
Author
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Done, added #include <limits>
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Summary
Add integer overflow check in
MaxCompressedLength()to preventheap buffer overflow vulnerabilities.
Problem
The expression
32 + source_bytes + source_bytes / 6can overflowwhen
source_bytesis very large, resulting in a small return value.Callers use this value to allocate buffers, so an overflow leads to
undersized allocations and subsequent heap buffer overflows during
compression.
Fix
Added a bounds check before the calculation. If
source_bytesexceedsthe safe threshold
(SIZE_MAX - 32) / 7 * 6, the function returnsSIZE_MAX, which forces a controlled allocation failure instead ofsilent memory corruption.