From b70fdbd2530dd18e1334ab06b0ab9fefc268a724 Mon Sep 17 00:00:00 2001 From: Konstantin Khlebnikov Date: Thu, 7 Aug 2014 20:52:43 +0400 Subject: [PATCH] Smack: handle zero-length security labels without panic Zero-length security labels are invalid but kernel should handle them. This patch fixes kernel panic after setting zero-length security labels: And after writing zero-length string into smackfs files syslog and onlycp: The problem is caused by brain-damaged logic in function smk_parse_smack() which takes pointer to buffer and its length but if length below or equal zero it thinks that the buffer is zero-terminated. Unfortunately callers of this function are widely used and proper fix requires serious refactoring. Change-Id: Icf462c7ac2464d86093fa42a0ed012281b952571 Signed-off-by: Konstantin Khlebnikov --- security/smack/smack_lsm.c | 2 +- security/smack/smackfs.c | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-) diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c index 6a64be6..541ee58 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -923,7 +923,7 @@ static int smack_inode_setxattr(struct dentry *dentry, const char *name, rc = -EPERM; if (rc == 0 && check_import) { - skp = smk_import_entry(value, size); + skp = size ? smk_import_entry(value, size) : NULL; if (skp == NULL || (check_star && (skp == &smack_known_star || skp == &smack_known_web))) rc = -EINVAL; diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c index 32b2488..585bea0 100644 --- a/security/smack/smackfs.c +++ b/security/smack/smackfs.c @@ -1677,7 +1677,7 @@ static ssize_t smk_write_onlycap(struct file *file, const char __user *buf, if (smack_onlycap != NULL && smack_onlycap != skp) return -EPERM; - data = kzalloc(count, GFP_KERNEL); + data = kzalloc(count + 1, GFP_KERNEL); if (data == NULL) return -ENOMEM; @@ -2228,7 +2228,7 @@ static ssize_t smk_write_syslog(struct file *file, const char __user *buf, if (!smack_privileged(CAP_MAC_ADMIN)) return -EPERM; - data = kzalloc(count, GFP_KERNEL); + data = kzalloc(count + 1, GFP_KERNEL); if (data == NULL) return -ENOMEM; -- 2.7.4