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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Pierre Ducroquet <pinaraf@pinaraf.info>,
        PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.15 049/128] crypto: ecc - Fix NULL pointer deref. on no default_rng
Date:   Fri, 16 Mar 2018 16:23:10 +0100
Message-Id: <20180316152339.283206824@linuxfoundation.org>
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4.15-stable review patch.  If anyone has any objections, please let me know.

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

From: Pierre <pinaraf@pinaraf.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@pinaraf.info>
Reviewed-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 crypto/ecc.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/crypto/ecc.c
+++ b/crypto/ecc.c
@@ -964,7 +964,7 @@ int ecc_gen_privkey(unsigned int curve_i
 	 * 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();