linux-kernel - [PATCH 4.9 029/119] crypto: drbg - wait for crypto op not signal safe

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Date:   Mon, 12 Jun 2017 17:24:51 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Eric Biggers <ebiggers3@...il.com>,
        Gilad Ben-Yossef <gilad@...yossef.com>,
        Herbert Xu <herbert@...dor.apana.org.au>
Subject: [PATCH 4.9 029/119] crypto: drbg - wait for crypto op not signal safe

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

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

From: Gilad Ben-Yossef <gilad@...yossef.com>

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@...il.com>
Signed-off-by: Gilad Ben-Yossef <gilad@...yossef.com>
Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 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;
 			}