[56_maintenance] Prevent buffer builder length overflow in MutableBuffer::extend_zeros (#9820)#9915
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alamb
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…s` (apache#9820) - None. BufferBuilder reserve paths relied on unchecked usize arithmetic when calculating the required byte length. In optimized builds, very large requested lengths could wrap before capacity growth. This adds checked arithmetic for MutableBuffer byte length calculations used by reserve and zero-extension paths. Yes. This adds regression coverage for overflowing BufferBuilder length calculations through reserve, append_n_zeroed, and advance. Invalid requested lengths whose byte size cannot be represented without overflow now panic consistently. There are no API changes.
etseidl
approved these changes
May 6, 2026
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| /// Allocates a new [MutableBuffer] with `len` and capacity to be at least `len` where | ||
| /// all bytes are guaranteed to be `0u8`. | ||
| /// |
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Will this be forward ported? 😂
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🦅 👁️
I guess Codex couldn't resist. I will resist my personal temptation to actually forward port it to avoid needlessly burning carbon. Though it would help pump up my github stats 🙄 (though now with the AI tools those metrics are much less informative 🤔 )
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56.2.1(May 2026) #9857This PR:
MutableBuffer::extend_zeros#9820 from @alamb to the56_maintenanceline