linux-kernel - [PATCH v2 2/4] crypto: drbg wait for crypto op not signal safe

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Message-Id: <1495114167-3073-3-git-send-email-gilad@benyossef.com>
Date:   Thu, 18 May 2017 16:29:24 +0300
From:   Gilad Ben-Yossef <gilad@...yossef.com>
To:     Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        Jonathan Corbet <corbet@....net>,
        David Howells <dhowells@...hat.com>
Cc:     Ofir Drang <ofir.drang@....com>, stable@...r.kernel.org,
        linux-crypto@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, keyrings@...r.kernel.org
Subject: [PATCH v2 2/4] 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@...il.com>
Signed-off-by: Gilad Ben-Yossef <gilad@...yossef.com>
CC: stable@...r.kernel.org
---
 crypto/drbg.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/crypto/drbg.c b/crypto/drbg.c
index fa749f4..cdb27ac 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;
 			}
-- 
2.1.4