Re: [PATCH] random: In _extract_crng() mix in 64 bits if possible

[Sandy Harris <sandyinchina@xxxxxxxxx>]

On many machines arch_get_random_long() gives 64 bits
but current code uses only 32 of them since it XORs
the result into p[14] which is u32.
---
My previous patch made an unwarranted assumption that
an array declared u32 would be 64-bit aligned. Thanks to
Eric for catching that.

This version avoids that problem and also handles the case
where on some machines a long is only 32 bits.

 drivers/char/random.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 605969ed0f96..2c6b56cf8b27 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -989,14 +989,19 @@ static void _extract_crng(struct crng_state *crng,
               __u8 out[CHACHA_BLOCK_SIZE])
 {
     unsigned long v, flags;
+        u32 *q ;
+        q = (u32 *) &v ;

     if (crng_ready() &&
         (time_after(crng_global_init_time, crng->init_time) ||
          time_after(jiffies, crng->init_time + CRNG_RESEED_INTERVAL)))
         crng_reseed(crng, crng == &primary_crng ? &input_pool : NULL);
     spin_lock_irqsave(&crng->lock, flags);
-    if (arch_get_random_long(&v))
-        crng->state[14] ^= v;
+    if (arch_get_random_long(&v))  {
+                p[14] ^= q[0] ;
+                if (sizeof(v) == 8)
+                        p[15] ^= q[1] ;
+        }
     chacha20_block(&crng->state[0], out);
     if (crng->state[12] == 0)
         crng->state[13]++;