Re: [PATCH 0/2] lib/crypto: chacha: Handle lengths of 2 GiB or more on 32-bit arm and MIPS

[Eric Biggers <ebiggers@kernel.org>]

On Wed, Oct 14, 2026 at 08:34:20PM +0000, Vladimir Kukharenko via B4 Relay wrote:
> On 32-bit arm (the scalar code) and 32-bit MIPS, the ChaCha assembly
> treats the length as signed, so lengths of 2 GiB or more are still
> mishandled after "lib/crypto: chacha: Use size_t length", since size_t
> is 32 bits there.
> 
> Patch 1 makes the arm assembly use unsigned conditions.  The MIPS
> assembly relies on the sign of the remaining length, so patch 2 instead
> limits each call to 1 GiB from C.
> 
> This applies on top of
> https://lore.kernel.org/r/20261014152604.323310-1-ebiggers@kernel.org
> Feel free to fold these into your series instead.
> 
> Tested with the lib/crypto KUnit tests in QEMU on arm (Cortex-A7 and
> Cortex-A15) and 32-bit MIPS, plus a temporary 2 GiB test on the
> Cortex-A7 and QEMU user mode runs of the MIPS assembly.
> 
> An LLM review found these bugs; I used an LLM-based assistant to write
> the patches and reviewed its work.
> 
> ---

Applied to https://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux.git/log/?h=libcrypto-next

- Eric