linux-kernel - [PATCH 3.16 171/410] CIFS: zero sensitive data when freeing

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Message-ID: <lsq.1528380321.881015899@decadent.org.uk>
Date:   Thu, 07 Jun 2018 15:05:21 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Aurelien Aptel" <aaptel@...e.com>,
        "Pavel Shilovsky" <pshilov@...rosoft.com>,
        "Steve French" <smfrench@...il.com>
Subject: [PATCH 3.16 171/410] CIFS: zero sensitive data when freeing

3.16.57-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Aurelien Aptel <aaptel@...e.com>

commit 97f4b7276b829a8927ac903a119bef2f963ccc58 upstream.

also replaces memset()+kfree() by kzfree().

Signed-off-by: Aurelien Aptel <aaptel@...e.com>
Signed-off-by: Steve French <smfrench@...il.com>
Reviewed-by: Pavel Shilovsky <pshilov@...rosoft.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 fs/cifs/cifsencrypt.c |  3 +--
 fs/cifs/connect.c     |  6 +++---
 fs/cifs/misc.c        | 14 ++++----------
 3 files changed, 8 insertions(+), 15 deletions(-)

--- a/fs/cifs/cifsencrypt.c
+++ b/fs/cifs/cifsencrypt.c
@@ -303,9 +303,8 @@ int calc_lanman_hash(const char *passwor
 {
 	int i;
 	int rc;
-	char password_with_pad[CIFS_ENCPWD_SIZE];
+	char password_with_pad[CIFS_ENCPWD_SIZE] = {0};
 
-	memset(password_with_pad, 0, CIFS_ENCPWD_SIZE);
 	if (password)
 		strncpy(password_with_pad, password, CIFS_ENCPWD_SIZE);
 
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -1614,7 +1614,7 @@ cifs_parse_mount_options(const char *mou
 			tmp_end++;
 			if (!(tmp_end < end && tmp_end[1] == delim)) {
 				/* No it is not. Set the password to NULL */
-				kfree(vol->password);
+				kzfree(vol->password);
 				vol->password = NULL;
 				break;
 			}
@@ -1652,7 +1652,7 @@ cifs_parse_mount_options(const char *mou
 					options = end;
 			}
 
-			kfree(vol->password);
+			kzfree(vol->password);
 			/* Now build new password string */
 			temp_len = strlen(value);
 			vol->password = kzalloc(temp_len+1, GFP_KERNEL);
@@ -4039,7 +4039,7 @@ cifs_construct_tcon(struct cifs_sb_info
 		reset_cifs_unix_caps(0, tcon, NULL, vol_info);
 out:
 	kfree(vol_info->username);
-	kfree(vol_info->password);
+	kzfree(vol_info->password);
 	kfree(vol_info);
 
 	return tcon;
--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -99,14 +99,11 @@ sesInfoFree(struct cifs_ses *buf_to_free
 	kfree(buf_to_free->serverOS);
 	kfree(buf_to_free->serverDomain);
 	kfree(buf_to_free->serverNOS);
-	if (buf_to_free->password) {
-		memset(buf_to_free->password, 0, strlen(buf_to_free->password));
-		kfree(buf_to_free->password);
-	}
+	kzfree(buf_to_free->password);
 	kfree(buf_to_free->user_name);
 	kfree(buf_to_free->domainName);
-	kfree(buf_to_free->auth_key.response);
-	kfree(buf_to_free);
+	kzfree(buf_to_free->auth_key.response);
+	kzfree(buf_to_free);
 }
 
 struct cifs_tcon *
@@ -137,10 +134,7 @@ tconInfoFree(struct cifs_tcon *buf_to_fr
 	}
 	atomic_dec(&tconInfoAllocCount);
 	kfree(buf_to_free->nativeFileSystem);
-	if (buf_to_free->password) {
-		memset(buf_to_free->password, 0, strlen(buf_to_free->password));
-		kfree(buf_to_free->password);
-	}
+	kzfree(buf_to_free->password);
 	kfree(buf_to_free);
 }