1 files changed, 31 insertions, 23 deletions

diff --git a/drivers/char/random.c b/drivers/char/random.c
index cd9a621..35487e8 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -865,16 +865,24 @@ static size_t account(struct entropy_store *r, size_t nbytes, int min,
 	if (r->entropy_count / 8 < min + reserved) {
 		nbytes = 0;
 	} else {
+		int entropy_count, orig;
+retry:
+		entropy_count = orig = ACCESS_ONCE(r->entropy_count);
 		/* If limited, never pull more than available */
-		if (r->limit && nbytes + reserved >= r->entropy_count / 8)
-			nbytes = r->entropy_count/8 - reserved;
-
-		if (r->entropy_count / 8 >= nbytes + reserved)
-			r->entropy_count -= nbytes*8;
-		else
-			r->entropy_count = reserved;
+		if (r->limit && nbytes + reserved >= entropy_count / 8)
+			nbytes = entropy_count/8 - reserved;
+
+		if (entropy_count / 8 >= nbytes + reserved) {
+			entropy_count -= nbytes*8;
+			if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig)
+				goto retry;
+		} else {
+			entropy_count = reserved;
+			if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig)
+				goto retry;
+		}
 
-		if (r->entropy_count < random_write_wakeup_thresh)
+		if (entropy_count < random_write_wakeup_thresh)
 			wakeup_write = 1;
 	}
 
@@ -957,10 +965,23 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf,
 {
 	ssize_t ret = 0, i;
 	__u8 tmp[EXTRACT_SIZE];
+	unsigned long flags;
 
 	/* if last_data isn't primed, we need EXTRACT_SIZE extra bytes */
-	if (fips_enabled && !r->last_data_init)
-		nbytes += EXTRACT_SIZE;
+	if (fips_enabled) {
+		spin_lock_irqsave(&r->lock, flags);
+		if (!r->last_data_init) {
+			r->last_data_init = true;
+			spin_unlock_irqrestore(&r->lock, flags);
+			trace_extract_entropy(r->name, EXTRACT_SIZE,
+					      r->entropy_count, _RET_IP_);
+			xfer_secondary_pool(r, EXTRACT_SIZE);
+			extract_buf(r, tmp);
+			spin_lock_irqsave(&r->lock, flags);
+			memcpy(r->last_data, tmp, EXTRACT_SIZE);
+		}
+		spin_unlock_irqrestore(&r->lock, flags);
+	}
 
 	trace_extract_entropy(r->name, nbytes, r->entropy_count, _RET_IP_);
 	xfer_secondary_pool(r, nbytes);
@@ -970,19 +991,6 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf,
 		extract_buf(r, tmp);
 
 		if (fips_enabled) {
-			unsigned long flags;
-
-
-			/* prime last_data value if need be, per fips 140-2 */
-			if (!r->last_data_init) {
-				spin_lock_irqsave(&r->lock, flags);
-				memcpy(r->last_data, tmp, EXTRACT_SIZE);
-				r->last_data_init = true;
-				nbytes -= EXTRACT_SIZE;
-				spin_unlock_irqrestore(&r->lock, flags);
-				extract_buf(r, tmp);
-			}
-
 			spin_lock_irqsave(&r->lock, flags);
 			if (!memcmp(tmp, r->last_data, EXTRACT_SIZE))
 				panic("Hardware RNG duplicated output!\n");