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@xxxxxxxxxxxxxxx>
Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
---
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@xxxxx>
*/
#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,
}
--
2.20.1
