linux-kernel - [PATCH v2 7/7] fs: HKDF - remove duplicate memory clearing

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Date:   Sun, 24 Jan 2021 15:04:50 +0100
From:   Stephan Müller <smueller@...onox.de>
To:     herbert@...dor.apana.org.au
Cc:     ebiggers@...nel.org, Jarkko Sakkinen <jarkko@...nel.org>,
        mathew.j.martineau@...ux.intel.com, dhowells@...hat.com,
        linux-crypto@...r.kernel.org, linux-fscrypt@...r.kernel.org,
        linux-kernel@...r.kernel.org, keyrings@...r.kernel.org,
        simo@...hat.com
Subject: [PATCH v2 7/7] fs: HKDF - remove duplicate memory clearing

The clearing of the OKM memory buffer in case of an error is already
performed by the HKDF implementation crypto_hkdf_expand. Thus, the
code clearing is not needed any more in the file system code base.

Signed-off-by: Stephan Mueller <smueller@...onox.de>
---
 fs/crypto/hkdf.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/fs/crypto/hkdf.c b/fs/crypto/hkdf.c
index ae236b42b1f0..c48dd8ca3a46 100644
--- a/fs/crypto/hkdf.c
+++ b/fs/crypto/hkdf.c
@@ -102,13 +102,10 @@ int fscrypt_hkdf_expand(const struct fscrypt_hkdf *hkdf, u8 context,
 		.iov_base = (u8 *)info,
 		.iov_len = infolen,
 	} };
-	int err = crypto_hkdf_expand(hkdf->hmac_tfm,
-				     info_iov, ARRAY_SIZE(info_iov),
-				     okm, okmlen);
 
-	if (unlikely(err))
-		memzero_explicit(okm, okmlen); /* so caller doesn't need to */
-	return err;
+	return crypto_hkdf_expand(hkdf->hmac_tfm,
+				  info_iov, ARRAY_SIZE(info_iov),
+				  okm, okmlen);
 }
 
 void fscrypt_destroy_hkdf(struct fscrypt_hkdf *hkdf)
-- 
2.26.2