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crypto: chacha20 - Fix keystream alignment for chacha20_block()

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When chacha20_block() outputs the keystream block, it uses 'u32' stores
directly.  However, the callers (crypto/chacha20_generic.c and
drivers/char/random.c) declare the keystream buffer as a 'u8' array,
which is not guaranteed to have the needed alignment.

Fix it by having both callers declare the keystream as a 'u32' array.
For now this is preferable to switching over to the unaligned access
macros because chacha20_block() is only being used in cases where we can
easily control the alignment (stack buffers).

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Eric Biggers
2017-11-22 11:51:39 -08:00
committed by Herbert Xu
parent 796c99fbd7
commit 9f480faec5
4 changed files with 18 additions and 17 deletions
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6
crypto/chacha20_generic.c
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@@ -18,20 +18,20 @@
static void chacha20_docrypt(u32 *state, u8 *dst, const u8 *src,
unsigned int bytes)
{
u8 stream[CHACHA20_BLOCK_SIZE];
u32 stream[CHACHA20_BLOCK_WORDS];
if (dst != src)
memcpy(dst, src, bytes);
while (bytes >= CHACHA20_BLOCK_SIZE) {
chacha20_block(state, stream);
crypto_xor(dst, stream, CHACHA20_BLOCK_SIZE);
crypto_xor(dst, (const u8 *)stream, CHACHA20_BLOCK_SIZE);
bytes -= CHACHA20_BLOCK_SIZE;
dst += CHACHA20_BLOCK_SIZE;
}
if (bytes) {
chacha20_block(state, stream);
crypto_xor(dst, stream, bytes);
crypto_xor(dst, (const u8 *)stream, bytes);
}
}