linux-kernel - [PATCH AUTOSEL for 4.14 16/84] crypto: ecc - Fix NULL pointer deref. on no default

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Message-ID: <20180303222518.26271-16-alexander.levin@microsoft.com>
Date:   Sat, 3 Mar 2018 22:26:09 +0000
From:   Sasha Levin <Alexander.Levin@...rosoft.com>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
CC:     Pierre <pinaraf@...araf.info>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Sasha Levin <Alexander.Levin@...rosoft.com>
Subject: [PATCH AUTOSEL for 4.14 16/84] crypto: ecc - Fix NULL pointer deref.
 on no default_rng

From: Pierre <pinaraf@...araf.info>

[ Upstream commit 4c0e22c90510308433272d7ba281b1eb4eda8209 ]

If crypto_get_default_rng returns an error, the
function ecc_gen_privkey should return an error.
Instead, it currently tries to use the default_rng
nevertheless, thus creating a kernel panic with a
NULL pointer dereference.
Returning the error directly, as was supposedly
intended when looking at the code, fixes this.

Signed-off-by: Pierre Ducroquet <pinaraf@...araf.info>
Reviewed-by: PrasannaKumar Muralidharan <prasannatsmkumar@...il.com>
Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
---
 crypto/ecc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/crypto/ecc.c b/crypto/ecc.c
index 633a9bcdc574..18f32f2a5e1c 100644
--- a/crypto/ecc.c
+++ b/crypto/ecc.c
@@ -964,7 +964,7 @@ int ecc_gen_privkey(unsigned int curve_id, unsigned int ndigits, u64 *privkey)
 	 * DRBG with a security strength of 256.
 	 */
 	if (crypto_get_default_rng())
-		err = -EFAULT;
+		return -EFAULT;
 
 	err = crypto_rng_get_bytes(crypto_default_rng, (u8 *)priv, nbytes);
 	crypto_put_default_rng();
-- 
2.14.1