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    Subject[PATCH URGENT crypto v2] crypto: arm64/chacha - correctly walk through blocks
    Date
    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@esmil.dk>
    Cc: Ard Biesheuvel <ardb@kernel.org>
    Cc: stable@vger.kernel.org # v5.5+
    Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
    ---
    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);

    --
    2.25.1
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