crypto: drbg - wait for crypto op not signal safe

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@gmail.com>
Signed-off-by: Gilad Ben-Yossef <gilad@benyossef.com>
CC: stable@vger.kernel.org
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 2 insertions, 3 deletions

diff --git a/crypto/drbg.c b/crypto/drbg.c
index fa749f470135..cdb27ac4b226 100644
--- a/crypto/drbg.c
+++ b/crypto/drbg.c
@@ -1767,9 +1767,8 @@ static int drbg_kcapi_sym_ctr(struct drbg_state *drbg,
                         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;
                         }