linux-kernel - [PATCH 3.16 091/204] Smack: remove unneeded NULL-termination from securtity label

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Date:   Thu, 28 Dec 2017 17:05:44 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Konstantin Khlebnikov" <k.khlebnikov@...sung.com>
Subject: [PATCH 3.16 091/204] Smack: remove unneeded NULL-termination from
 securtity label

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

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

From: Konstantin Khlebnikov <k.khlebnikov@...sung.com>

commit da1b63566c469bf3e2b24182114422e16b1aa34c upstream.

Values of extended attributes are stored as binary blobs. NULL-termination
of them isn't required. It just wastes disk space and confuses command-line
tools like getfattr because they have to print that zero byte at the end.

This patch removes terminating zero byte from initial security label in
smack_inode_init_security and cuts it out in function smack_inode_getsecurity
which is used by syscall getxattr. This change seems completely safe, because
function smk_parse_smack ignores everything after first zero byte.

Signed-off-by: Konstantin Khlebnikov <k.khlebnikov@...sung.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 security/smack/smack_lsm.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -674,7 +674,7 @@ static int smack_inode_init_security(str
 	}

 	if (len)
-		*len = strlen(isp) + 1;
+		*len = strlen(isp);

 	return 0;
 }
@@ -1078,7 +1078,7 @@ static int smack_inode_getsecurity(const

 	if (strcmp(name, XATTR_SMACK_SUFFIX) == 0) {
 		isp = smk_of_inode(inode);
-		ilen = strlen(isp) + 1;
+		ilen = strlen(isp);
 		*buffer = isp;
 		return ilen;
 	}
@@ -1103,7 +1103,7 @@ static int smack_inode_getsecurity(const
 	else
 		return -EOPNOTSUPP;

-	ilen = strlen(isp) + 1;
+	ilen = strlen(isp);
 	if (rc == 0) {
 		*buffer = isp;
 		rc = ilen;