On Wed, Mar 18, 2020 at 08:27:32PM -0600, Jason A. Donenfeld wrote:
> Prior, passing in chunks of 2, 3, or 4, followed by any additional
> chunks would result in the chacha state counter getting out of sync,
> resulting in incorrect encryption/decryption, which is a pretty nasty
> crypto vuln: "why do images look weird on webpages?" WireGuard users
> never experienced this prior, because we have always, out of tree, used
> a different crypto library, until the recent Frankenzinc addition. This
> commit fixes the issue by advancing the pointers and state counter by
> the actual size processed. It also fixes up a bug in the (optional,
> costly) stride test that prevented it from running on arm64.
>
> Fixes: b3aad5bad26a ("crypto: arm64/chacha - expose arm64 ChaCha routine as library function")
> Reported-and-tested-by: Emil Renner Berthing <kernel@xxxxxxxx>
> Cc: Ard Biesheuvel <ardb@xxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx # v5.5+
> Signed-off-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
> ---
> arch/arm64/crypto/chacha-neon-glue.c | 8 ++++----
> lib/crypto/chacha20poly1305-selftest.c | 11 ++++++++---
> 2 files changed, 12 insertions(+), 7 deletions(-)
>
> diff --git a/arch/arm64/crypto/chacha-neon-glue.c b/arch/arm64/crypto/chacha-neon-glue.c
> index c1f9660d104c..37ca3e889848 100644
> --- a/arch/arm64/crypto/chacha-neon-glue.c
> +++ b/arch/arm64/crypto/chacha-neon-glue.c
> @@ -55,10 +55,10 @@ static void chacha_doneon(u32 *state, u8 *dst, const u8 *src,
> break;
> }
> chacha_4block_xor_neon(state, dst, src, nrounds, l);
> - bytes -= CHACHA_BLOCK_SIZE * 5;
> - src += CHACHA_BLOCK_SIZE * 5;
> - dst += CHACHA_BLOCK_SIZE * 5;
> - state[12] += 5;
> + bytes -= l;
> + src += l;
> + dst += l;
> + state[12] += DIV_ROUND_UP(l, CHACHA_BLOCK_SIZE);
> }
> }
>
> diff --git a/lib/crypto/chacha20poly1305-selftest.c b/lib/crypto/chacha20poly1305-selftest.c
> index c391a91364e9..fa43deda2660 100644
> --- a/lib/crypto/chacha20poly1305-selftest.c
> +++ b/lib/crypto/chacha20poly1305-selftest.c
> @@ -9028,10 +9028,15 @@ bool __init chacha20poly1305_selftest(void)
> && total_len <= 1 << 10; ++total_len) {
> for (i = 0; i <= total_len; ++i) {
> for (j = i; j <= total_len; ++j) {
> + k = 0;
> sg_init_table(sg_src, 3);
> - sg_set_buf(&sg_src[0], input, i);
> - sg_set_buf(&sg_src[1], input + i, j - i);
> - sg_set_buf(&sg_src[2], input + j, total_len - j);
> + if (i)
> + sg_set_buf(&sg_src[k++], input, i);
> + if (j - i)
> + sg_set_buf(&sg_src[k++], input + i, j - i);
> + if (total_len - j)
> + sg_set_buf(&sg_src[k++], input + j, total_len - j);
> + sg_init_marker(sg_src, k);
> memset(computed_output, 0, total_len);
> memset(input, 0, total_len);
>
Reviewed-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Herbert, can you send this to Linus for 5.6?
- Eric
