crypto: chacha20 - Fix keystream alignment for chacha20_block()

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>

1 files changed, 12 insertions, 12 deletions

diff --git a/drivers/char/random.c b/drivers/char/random.c
index ec42c8bb9b0d..11304bbc78cc 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -431,9 +431,9 @@ static int crng_init = 0;
 static int crng_init_cnt = 0;
 #define CRNG_INIT_CNT_THRESH (2*CHACHA20_KEY_SIZE)
 static void _extract_crng(struct crng_state *crng,
-                          __u8 out[CHACHA20_BLOCK_SIZE]);
+                          __u32 out[CHACHA20_BLOCK_WORDS]);
 static void _crng_backtrack_protect(struct crng_state *crng,
-                                    __u8 tmp[CHACHA20_BLOCK_SIZE], int used);
+                                    __u32 tmp[CHACHA20_BLOCK_WORDS], int used);
 static void process_random_ready_list(void);
 static void _get_random_bytes(void *buf, int nbytes);
 
@@ -817,7 +817,7 @@ static void crng_reseed(struct crng_state *crng, struct entropy_store *r)
         unsigned long   flags;
         int             i, num;
         union {
-                __u8    block[CHACHA20_BLOCK_SIZE];
+                __u32   block[CHACHA20_BLOCK_WORDS];
                 __u32   key[8];
         } buf;
 
@@ -851,7 +851,7 @@ static void crng_reseed(struct crng_state *crng, struct entropy_store *r)
 }
 
 static void _extract_crng(struct crng_state *crng,
-                          __u8 out[CHACHA20_BLOCK_SIZE])
+                          __u32 out[CHACHA20_BLOCK_WORDS])
 {
         unsigned long v, flags;
 
@@ -867,7 +867,7 @@ static void _extract_crng(struct crng_state *crng,
         spin_unlock_irqrestore(&crng->lock, flags);
 }
 
-static void extract_crng(__u8 out[CHACHA20_BLOCK_SIZE])
+static void extract_crng(__u32 out[CHACHA20_BLOCK_WORDS])
 {
         struct crng_state *crng = NULL;
 
@@ -885,7 +885,7 @@ static void extract_crng(__u8 out[CHACHA20_BLOCK_SIZE])
  * enough) to mutate the CRNG key to provide backtracking protection.
  */
 static void _crng_backtrack_protect(struct crng_state *crng,
-                                    __u8 tmp[CHACHA20_BLOCK_SIZE], int used)
+                                    __u32 tmp[CHACHA20_BLOCK_WORDS], int used)
 {
         unsigned long   flags;
         __u32           *s, *d;
@@ -897,14 +897,14 @@ static void _crng_backtrack_protect(struct crng_state *crng,
                 used = 0;
         }
         spin_lock_irqsave(&crng->lock, flags);
-        s = (__u32 *) &tmp[used];
+        s = &tmp[used / sizeof(__u32)];
         d = &crng->state[4];
         for (i=0; i < 8; i++)
                 *d++ ^= *s++;
         spin_unlock_irqrestore(&crng->lock, flags);
 }
 
-static void crng_backtrack_protect(__u8 tmp[CHACHA20_BLOCK_SIZE], int used)
+static void crng_backtrack_protect(__u32 tmp[CHACHA20_BLOCK_WORDS], int used)
 {
         struct crng_state *crng = NULL;
 
@@ -920,7 +920,7 @@ static void crng_backtrack_protect(__u8 tmp[CHACHA20_BLOCK_SIZE], int used)
 static ssize_t extract_crng_user(void __user *buf, size_t nbytes)
 {
         ssize_t ret = 0, i = CHACHA20_BLOCK_SIZE;
-        __u8 tmp[CHACHA20_BLOCK_SIZE];
+        __u32 tmp[CHACHA20_BLOCK_WORDS];
         int large_request = (nbytes > 256);
 
         while (nbytes) {
@@ -1507,7 +1507,7 @@ static void _warn_unseeded_randomness(const char *func_name, void *caller,
  */
 static void _get_random_bytes(void *buf, int nbytes)
 {
-        __u8 tmp[CHACHA20_BLOCK_SIZE];
+        __u32 tmp[CHACHA20_BLOCK_WORDS];
 
         trace_get_random_bytes(nbytes, _RET_IP_);
 
@@ -2114,7 +2114,7 @@ u64 get_random_u64(void)
         if (use_lock)
                 read_lock_irqsave(&batched_entropy_reset_lock, flags);
         if (batch->position % ARRAY_SIZE(batch->entropy_u64) == 0) {
-                extract_crng((u8 *)batch->entropy_u64);
+                extract_crng((__u32 *)batch->entropy_u64);
                 batch->position = 0;
         }
         ret = batch->entropy_u64[batch->position++];
@@ -2144,7 +2144,7 @@ u32 get_random_u32(void)
         if (use_lock)
                 read_lock_irqsave(&batched_entropy_reset_lock, flags);
         if (batch->position % ARRAY_SIZE(batch->entropy_u32) == 0) {
-                extract_crng((u8 *)batch->entropy_u32);
+                extract_crng(batch->entropy_u32);
                 batch->position = 0;
         }
         ret = batch->entropy_u32[batch->position++];