[PATCH v2 2/6] smb: clear the aes_cmac_key and aes_cmac_ctx when done

[Thomas Huth <thuth@redhat.com>]

From: Thomas Huth <thuth@redhat.com>

Clear the local crypto-related structures via __cleanup() functions
when we're done with them to avoid that sensitive data could leak on
the stack.

Note: cmac_ctx in ksmbd_sign_smb3_pdu() gets cleared in aes_cmac_final()
already, so this does not need a __cleanup() marker.

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 fs/smb/client/smb2transport.c | 4 ++--
 fs/smb/server/auth.c          | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/smb/client/smb2transport.c b/fs/smb/client/smb2transport.c
index 1143ee52470a7..d23566da2ac81 100644
--- a/fs/smb/client/smb2transport.c
+++ b/fs/smb/client/smb2transport.c
@@ -464,8 +464,8 @@ smb3_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 	unsigned char smb3_signature[SMB2_CMACAES_SIZE];
 	struct kvec *iov = rqst->rq_iov;
 	struct smb2_hdr *shdr = (struct smb2_hdr *)iov[0].iov_base;
-	struct aes_cmac_key cmac_key;
-	struct aes_cmac_ctx cmac_ctx;
+	struct aes_cmac_key cmac_key __cleanup(aes_cmac_zeroize_key);
+	struct aes_cmac_ctx cmac_ctx __cleanup(aes_cmac_zeroize_ctx);
 	struct smb_rqst drqst;
 	u8 key[SMB3_SIGN_KEY_SIZE];
 
diff --git a/fs/smb/server/auth.c b/fs/smb/server/auth.c
index 4e7b6f0e6b8cd..e8d1c068a43e8 100644
--- a/fs/smb/server/auth.c
+++ b/fs/smb/server/auth.c
@@ -509,7 +509,7 @@ void ksmbd_sign_smb2_pdu(struct ksmbd_conn *conn, char *key, struct kvec *iov,
 void ksmbd_sign_smb3_pdu(struct ksmbd_conn *conn, char *key, struct kvec *iov,
 			 int n_vec, char *sig)
 {
-	struct aes_cmac_key cmac_key;
+	struct aes_cmac_key cmac_key __cleanup(aes_cmac_zeroize_key);
 	struct aes_cmac_ctx cmac_ctx;
 	int i;
 
-- 
2.55.0