crypto: asym_tpm: correct zero out potential secrets

gregkh · gregkh · commit f93274ef0fe9 · 2020-12-31T10:48:53.000+01:00
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. Cc: stable <stable@vger.kernel.org> Reported-by: Ilil Blum Shem-Tov <ilil.blum.shem-tov@intel.com> Tested-by: Ilil Blum Shem-Tov <ilil.blum.shem-tov@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Link: https://lore.kernel.org/r/X8ns4AfwjKudpyfe@kroah.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git 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;
 }

Original file line number	Diff line number	Diff line change
`@@ -354,7 +354,7 @@ static uint32_t derive_pub_key(const void pub_key, uint32_t len, uint8_t buf)`
`354`	`354`	`memcpy(cur, e, sizeof(e));`
`355`	`355`	`cur += sizeof(e);`
`356`	`356`	`/* Zero parameters to satisfy set_pub_key ABI. */`
`357`		`- memset(cur, 0, SETKEY_PARAMS_SIZE);`
	`357`	`+ memzero_explicit(cur, SETKEY_PARAMS_SIZE);`
`358`	`358`
`359`	`359`	`return cur - buf;`
`360`	`360`	`}`