The Michael MIC driver uses the cra_alignmask to ensure that pointers presented to its update and finup/final methods are 32-bit aligned. However, due to the way the shash API works, this is no guarantee that the 32-bit reads occurring in the update method are also aligned, as the size of the buffer presented to update may be of uneven length. For instance, an update() of 3 bytes followed by a misaligned update() of 4 or more bytes will result in a misaligned access using an accessor that is not suitable for this.

On most architectures, this does not matter, and so setting the cra_alignmask is pointless. On architectures where this does matter, setting the cra_alignmask does not actually solve the problem.

So let's get rid of the cra_alignmask, and use unaligned accessors instead, where appropriate.

Cc: stable@vger.kernel.org Signed-off-by: Ard Biesheuvel ardb@kernel.org --- crypto/michael_mic.c | 31 ++++++++------------ 1 file changed, 12 insertions(+), 19 deletions(-)

diff --git a/crypto/michael_mic.c b/crypto/michael_mic.c index 63350c4ad461..f4c31049601c 100644 --- a/crypto/michael_mic.c +++ b/crypto/michael_mic.c @@ -7,7 +7,7 @@ * Copyright (c) 2004 Jouni Malinen j@w1.fi */ #include <crypto/internal/hash.h> -#include <asm/byteorder.h> +#include <asm/unaligned.h> #include <linux/init.h> #include <linux/module.h> #include <linux/string.h> @@ -19,7 +19,7 @@ struct michael_mic_ctx { };

struct michael_mic_desc_ctx { - u8 pending[4]; + __le32 pending; size_t pending_len;

u32 l, r; @@ -60,13 +60,12 @@ static int michael_update(struct shash_desc *desc, const u8 *data, unsigned int len) { struct michael_mic_desc_ctx *mctx = shash_desc_ctx(desc); - const __le32 *src;

if (mctx->pending_len) { int flen = 4 - mctx->pending_len; if (flen > len) flen = len; - memcpy(&mctx->pending[mctx->pending_len], data, flen); + memcpy((u8 *)&mctx->pending + mctx->pending_len, data, flen); mctx->pending_len += flen; data += flen; len -= flen; @@ -74,23 +73,21 @@ static int michael_update(struct shash_desc *desc, const u8 *data, if (mctx->pending_len < 4) return 0;

- src = (const __le32 *)mctx->pending; - mctx->l ^= le32_to_cpup(src); + mctx->l ^= le32_to_cpu(mctx->pending); michael_block(mctx->l, mctx->r); mctx->pending_len = 0; }

- src = (const __le32 *)data; - while (len >= 4) { - mctx->l ^= le32_to_cpup(src++); + mctx->l ^= get_unaligned_le32(data); michael_block(mctx->l, mctx->r); + data += 4; len -= 4; }

if (len > 0) { mctx->pending_len = len; - memcpy(mctx->pending, src, len); + memcpy(&mctx->pending, data, len); }

return 0; @@ -100,8 +97,7 @@ static int michael_update(struct shash_desc *desc, const u8 *data, static int michael_final(struct shash_desc *desc, u8 *out) { struct michael_mic_desc_ctx *mctx = shash_desc_ctx(desc); - u8 *data = mctx->pending; - __le32 *dst = (__le32 *)out; + u8 *data = (u8 *)&mctx->pending;

/* Last block and padding (0x5a, 4..7 x 0) */ switch (mctx->pending_len) { @@ -123,8 +119,8 @@ static int michael_final(struct shash_desc *desc, u8 *out) /* l ^= 0; */ michael_block(mctx->l, mctx->r);

- dst[0] = cpu_to_le32(mctx->l); - dst[1] = cpu_to_le32(mctx->r); + put_unaligned_le32(mctx->l, out); + put_unaligned_le32(mctx->r, out + 4);

return 0; } @@ -135,13 +131,11 @@ static int michael_setkey(struct crypto_shash *tfm, const u8 *key, { struct michael_mic_ctx *mctx = crypto_shash_ctx(tfm);

- const __le32 *data = (const __le32 *)key; - if (keylen != 8) return -EINVAL;

- mctx->l = le32_to_cpu(data[0]); - mctx->r = le32_to_cpu(data[1]); + mctx->l = get_unaligned_le32(key); + mctx->r = get_unaligned_le32(key + 4); return 0; }

@@ -156,7 +150,6 @@ static struct shash_alg alg = { .cra_name = "michael_mic", .cra_driver_name = "michael_mic-generic", .cra_blocksize = 8, - .cra_alignmask = 3, .cra_ctxsize = sizeof(struct michael_mic_ctx), .cra_module = THIS_MODULE, }