BACKPORT: 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>

(cherry picked from commit 9f480faec58cd6197a007ea1dcac6b7c3daf1139)

Conflicts:
	drivers/char/random.c

Bug: 112008522
Test: As series, see Ic61c13b53facfd2173065be715a7ee5f3af8760b
Change-Id: I7557b2ca2ace0e19e97e997659857b3fa7a2b540
Signed-off-by: Eric Biggers <ebiggers@google.com>
4 files changed