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); -- 2.25.1