From b862e561bad6372872f5bf98d95f4131d265b110 Mon Sep 17 00:00:00 2001 From: Konstantin Khlebnikov Date: Thu, 7 Aug 2014 20:52:43 +0400 Subject: 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: # attr -S -s "SMACK64" -V "" file And after writing zero-length string into smackfs files syslog and onlycp: # python -c 'import os; os.write(1, "")' > /smack/syslog 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. Signed-off-by: Konstantin Khlebnikov --- security/smack/smackfs.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'security/smack/smackfs.c') diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c index 3c720ff10591..56a1439786a9 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; -- cgit v1.2.3