[PATCH] fscrypt: Explicitly zeroize sw_secret in error path

[Eric Biggers <ebiggers@kernel.org>]

Explicitly zeroize the sw_secret array in the case where
fscrypt_derive_sw_secret() fails, in case anything was written to it.
Doesn't really matter, but this came up in a code review.

Signed-off-by: Eric Biggers <ebiggers@kernel.org>
---
 fs/crypto/keyring.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/crypto/keyring.c b/fs/crypto/keyring.c
index 874cc183ee624..09364fddcb7a1 100644
--- a/fs/crypto/keyring.c
+++ b/fs/crypto/keyring.c
@@ -561,8 +561,10 @@ static int add_master_key(struct super_block *sb,
 		if (secret->is_hw_wrapped) {
 			err = fscrypt_derive_sw_secret(sb, secret->bytes,
 						       secret->size, sw_secret);
-			if (err)
+			if (err) {
+				memzero_explicit(sw_secret, sizeof(sw_secret));
 				return err;
+			}
 			kdf_key = sw_secret;
 			kdf_key_size = sizeof(sw_secret);
 			/*

base-commit: ccc4d9f8912a5d9f519a34c3633fe53c8f9b429e
-- 
2.56.0.218.g1ec904b173-goog