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Always write the Poly1305 tag to an aligned buffer.

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With GCC 4.9 and -O2 (and only -O2, -O1 and -O3 didn't trigger it), the
Poly1305 code can end up writing to an unaligned address otherwise and
that triggers a bus error on ARM.

Change-Id: Ifbeb7e2066a893d91d6f63c6565bac7d5542ef81
Reviewed-on: https://boringssl-review.googlesource.com/2850
Reviewed-by: Adam Langley <agl@google.com>
This commit is contained in:
Adam Langley 2015-01-12 17:19:51 -08:00
parent 3e6526575a
commit b1116a4a3b
2 changed files with 4 additions and 10 deletions
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8
crypto/cipher/e_chacha20poly1305.c
View File

@ -134,17 +134,11 @@ static int aead_chacha20_poly1305_seal(const EVP_AEAD_CTX *ctx, uint8_t *out,
CRYPTO_chacha_20(out, in, in_len, c20_ctx->key, nonce, 1);
poly1305_update_with_length(&poly1305, out, in_len);
if (c20_ctx->tag_len != POLY1305_TAG_LEN) {
uint8_t tag[POLY1305_TAG_LEN];
uint8_t tag[POLY1305_TAG_LEN] ALIGNED;
CRYPTO_poly1305_finish(&poly1305, tag);
memcpy(out + in_len, tag, c20_ctx->tag_len);
*out_len = in_len + c20_ctx->tag_len;
return 1;
}
CRYPTO_poly1305_finish(&poly1305, out + in_len);
*out_len = in_len + c20_ctx->tag_len;
return 1;
}
static int aead_chacha20_poly1305_open(const EVP_AEAD_CTX *ctx, uint8_t *out,

2
include/openssl/poly1305.h
View File

@ -36,7 +36,7 @@ extern void CRYPTO_poly1305_update(poly1305_state* state, const uint8_t* in,
size_t in_len);
/* poly1305_finish completes the poly1305 calculation and writes a 16 byte
* authentication tag to |mac|. */
* authentication tag to |mac|. The |mac| address must be 16-byte aligned. */
extern void CRYPTO_poly1305_finish(poly1305_state* state, uint8_t mac[16]);