diff options
| author | Samuel Neves <sneves@dei.uc.pt> | 2018-05-11 21:15:55 +0100 |
|---|---|---|
| committer | Jason A. Donenfeld <Jason@zx2c4.com> | 2018-05-13 16:58:53 +0200 |
| commit | ac659ac1f0a4b18d56b1fa0cc85cbbdff86e3494 (patch) | |
| tree | 83105089072768075789b190a25a387f73958bd9 | |
| parent | b2c20c032ab89e24c8210b1159348e48d917aea2 (diff) | |
chacha20poly1305: make gcc 8.1 happy
GCC 8.1 does not know about the invariant `0 <= ctx->num < POLY1305_BLOCK_SIZE`.
This results in a warning that `memcpy(ctx->data + num, inp, len);` may
overflow the `data` field, which is correct for arbitrary values of `num`.
To make the invariant explicit we ensure that `num` is in the required range.
An alternative would be to change `ctx->num` to a 4-bit bitfield at the point
of declaration.
This changes the code from `test ebp, ebp; jz end` to `and ebp, 15; jz
end`, which have identical performance characteristics.
Signed-off-by: Samuel Neves <sneves@dei.uc.pt>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
| -rw-r--r-- | src/crypto/chacha20poly1305.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/src/crypto/chacha20poly1305.c b/src/crypto/chacha20poly1305.c index 353cdf9..c066d93 100644 --- a/src/crypto/chacha20poly1305.c +++ b/src/crypto/chacha20poly1305.c @@ -536,7 +536,7 @@ static inline void poly1305_emit(void *ctx, u8 mac[16], const u32 nonce[4], bool static void poly1305_update(struct poly1305_ctx *ctx, const u8 *inp, size_t len, bool have_simd) { - const size_t num = ctx->num; + const size_t num = ctx->num % POLY1305_BLOCK_SIZE; size_t rem; if (num) { @@ -570,7 +570,7 @@ static void poly1305_update(struct poly1305_ctx *ctx, const u8 *inp, size_t len, static void poly1305_finish(struct poly1305_ctx *ctx, u8 mac[16], bool have_simd) { - size_t num = ctx->num; + size_t num = ctx->num % POLY1305_BLOCK_SIZE; if (num) { ctx->data[num++] = 1; /* pad bit */ |