linux-kernel - [PATCH 3/4] crypto: gcm wait for crypto op not signal safe

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Message-Id: <1494503626-15877-4-git-send-email-gilad@benyossef.com>
Date:   Thu, 11 May 2017 14:53:44 +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>,
        Gilad Ben-Yossef <gilad.benyossef@....com>,
        Eric Biggers <ebiggers3@...il.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 3/4] crypto: gcm wait for crypto op not signal safe

crypto_gcm_setkey() 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 data buffer that is kfree'ed in this case.

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 | 4 ++--
 crypto/gcm.c  | 6 ++----
 2 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/crypto/drbg.c b/crypto/drbg.c
index fa9054d..cdb27ac 100644
--- a/crypto/drbg.c
+++ b/crypto/drbg.c
@@ -1767,8 +1767,8 @@ static int drbg_kcapi_sym_ctr(struct drbg_state *drbg,
 			break;
 		case -EINPROGRESS:
 		case -EBUSY:
-			ret = wait_for_completion(&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;
 			}
diff --git a/crypto/gcm.c b/crypto/gcm.c
index b7ad808..3841b5e 100644
--- a/crypto/gcm.c
+++ b/crypto/gcm.c
@@ -152,10 +152,8 @@ static int crypto_gcm_setkey(struct crypto_aead *aead, const u8 *key,
 
 	err = crypto_skcipher_encrypt(&data->req);
 	if (err == -EINPROGRESS || err == -EBUSY) {
-		err = wait_for_completion_interruptible(
-			&data->result.completion);
-		if (!err)
-			err = data->result.err;
+		wait_for_completion(&data->result.completion);
+		err = data->result.err;
 	}
 
 	if (err)
-- 
2.1.4