[PATCH 4.11 041/150] crypto: drbg - wait for crypto op not signal safe

[Greg Kroah-Hartman]

4.11-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Gilad Ben-Yossef <gilad@xxxxxxxxxxxxx>

commit a5dfefb1c3f3db81662556393fd9283511e08430 upstream.

drbg_kcapi_sym_ctr() was using wait_for_completion_interruptible() to
wait for completion of async crypto op but if a signal occurs it
may return before DMA ops of HW crypto provider finish, thus
corrupting the output buffer.

Resolve this by using wait_for_completion() instead.

Reported-by: Eric Biggers <ebiggers3@xxxxxxxxx>
Signed-off-by: Gilad Ben-Yossef <gilad@xxxxxxxxxxxxx>
Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 crypto/drbg.c |    5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

--- a/crypto/drbg.c
+++ b/crypto/drbg.c
@@ -1768,9 +1768,8 @@ static int drbg_kcapi_sym_ctr(struct drb
 			break;
 		case -EINPROGRESS:
 		case -EBUSY:
-			ret = wait_for_completion_interruptible(
-				&drbg->ctr_completion);
-			if (!ret && !drbg->ctr_async_err) {
+			wait_for_completion(&drbg->ctr_completion);
+			if (!drbg->ctr_async_err) {
 				reinit_completion(&drbg->ctr_completion);
 				break;
 			}