cifs: clean up the SecurityFlags write handler

The SecurityFlags handler uses an obsolete simple_strtoul() call, and
doesn't really handle the bounds checking well. Fix it to use
kstrtouint() instead. Clean up the error messages as well and fix a
bogus check for an unsigned int to be less than 0.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: Pavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: Steve French <smfrench@gmail.com>

diff --git a/fs/cifs/cifs_debug.c b/fs/cifs/cifs_debug.c
index d597483..856f8f5 100644 (file)
--- a/fs/cifs/cifs_debug.c
+++ b/fs/cifs/cifs_debug.c
@@ -598,6 +598,7 @@ static int cifs_security_flags_proc_open(struct inode *inode, struct file *file)
 static ssize_t cifs_security_flags_proc_write(struct file *file,
                const char __user *buffer, size_t count, loff_t *ppos)
 {
+       int rc;
        unsigned int flags;
        char flags_string[12];
        char c;
@@ -620,26 +621,33 @@ static ssize_t cifs_security_flags_proc_write(struct file *file,
                        global_secflags = CIFSSEC_MAX;
                        return count;
                } else if (!isdigit(c)) {
-                       cifs_dbg(VFS, "invalid flag %c\n", c);
+                       cifs_dbg(VFS, "Invalid SecurityFlags: %s\n",
+                                       flags_string);
                        return -EINVAL;
                }
        }
-       /* else we have a number */
 
-       flags = simple_strtoul(flags_string, NULL, 0);
+       /* else we have a number */
+       rc = kstrtouint(flags_string, 0, &flags);
+       if (rc) {
+               cifs_dbg(VFS, "Invalid SecurityFlags: %s\n",
+                               flags_string);
+               return rc;
+       }
 
        cifs_dbg(FYI, "sec flags 0x%x\n", flags);
 
-       if (flags <= 0)  {
-               cifs_dbg(VFS, "invalid security flags %s\n", flags_string);
+       if (flags == 0)  {
+               cifs_dbg(VFS, "Invalid SecurityFlags: %s\n", flags_string);
                return -EINVAL;
        }
 
        if (flags & ~CIFSSEC_MASK) {
-               cifs_dbg(VFS, "attempt to set unsupported security flags 0x%x\n",
+               cifs_dbg(VFS, "Unsupported security flags: 0x%x\n",
                         flags & ~CIFSSEC_MASK);
                return -EINVAL;
        }
+
        /* flags look ok - update the global security flags for cifs module */
        global_secflags = flags;
        if (global_secflags & CIFSSEC_MUST_SIGN) {