linux-kernel - [PATCH] crypto: asym_tpm: correct zero out potential secrets

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Message-ID: <X8ns4AfwjKudpyfe@kroah.com>
Date:   Fri, 4 Dec 2020 09:01:36 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     David Howells <dhowells@...hat.com>,
        Herbert Xu <herbert@...dor.apana.org.au>
Cc:     "David S. Miller" <davem@...emloft.net>, keyrings@...r.kernel.org,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
        Ilil Blum Shem-Tov <ilil.blum.shem-tov@...el.com>
Subject: [PATCH] crypto: asym_tpm: correct zero out potential secrets

The function derive_pub_key() should be calling memzero_explicit()
instead of memset() in case the complier decides to optimize away the
call to memset() because it "knows" no one is going to touch the memory
anymore.

Reported-by: Ilil Blum Shem-Tov <ilil.blum.shem-tov@...el.com>
Tested-by: Ilil Blum Shem-Tov <ilil.blum.shem-tov@...el.com>
Cc: stable <stable@...r.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 crypto/asymmetric_keys/asym_tpm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/crypto/asymmetric_keys/asym_tpm.c b/crypto/asymmetric_keys/asym_tpm.c
index 378b18b9bc34..84a5d6af9609 100644
--- a/crypto/asymmetric_keys/asym_tpm.c
+++ b/crypto/asymmetric_keys/asym_tpm.c
@@ -354,7 +354,7 @@ static uint32_t derive_pub_key(const void *pub_key, uint32_t len, uint8_t *buf)
 	memcpy(cur, e, sizeof(e));
 	cur += sizeof(e);
 	/* Zero parameters to satisfy set_pub_key ABI. */
-	memset(cur, 0, SETKEY_PARAMS_SIZE);
+	memzero_explicit(cur, SETKEY_PARAMS_SIZE);
 
 	return cur - buf;
 }
-- 
2.29.2