Thread (16 messages) 16 messages, 3 authors, 2021-01-28

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

From: Eric Biggers <ebiggers@kernel.org>
Date: 2021-01-28 20:22:42
Also in: keyrings, linux-fscrypt, lkml

On Sun, Jan 24, 2021 at 03:04:50PM +0100, Stephan Müller wrote:
quoted hunk ↗ jump to hunk
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 <redacted>
---
 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);
 }
 
Shoudn't this just be folded into the previous patch, which converted
fscrypt_hkdf_expand() to use crypto_hkdf_expand() in the first place?

- Eric
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