ima: ima_write_policy() limit locking

There is no need to hold the ima_write_mutex for so long.  We only need it
around ima_parse_add_rule().

Changelog:
- The return path now takes into account failed kmalloc() call.

Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Petko Manolov <petkan@mip-labs.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

1 files changed, 9 insertions, 9 deletions

diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
index 3caed6de610c..f355231997b4 100644
--- a/security/integrity/ima/ima_fs.c
+++ b/security/integrity/ima/ima_fs.c
@@ -261,13 +261,8 @@ static const struct file_operations ima_ascii_measurements_ops = {
 static ssize_t ima_write_policy(struct file *file, const char __user *buf,
                                 size_t datalen, loff_t *ppos)
 {
-        char *data = NULL;
+        char *data;
         ssize_t result;
-        int res;
-
-        res = mutex_lock_interruptible(&ima_write_mutex);
-        if (res)
-                return res;
 
         if (datalen >= PAGE_SIZE)
                 datalen = PAGE_SIZE - 1;
@@ -286,14 +281,19 @@ static ssize_t ima_write_policy(struct file *file, const char __user *buf,
 
         result = -EFAULT;
         if (copy_from_user(data, buf, datalen))
-                goto out;
+                goto out_free;
 
+        result = mutex_lock_interruptible(&ima_write_mutex);
+        if (result < 0)
+                goto out_free;
         result = ima_parse_add_rule(data);
+        mutex_unlock(&ima_write_mutex);
+
+out_free:
+        kfree(data);
 out:
         if (result < 0)
                 valid_policy = 0;
-        kfree(data);
-        mutex_unlock(&ima_write_mutex);
 
         return result;
 }