cifs: return error on invalid value written to cifsFYI

RHBZ: 1539617

Check that, if it is not a boolean, the value the user tries
to write to /proc/fs/cifs/cifsFYI is valid and return an error
if not.

Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reported-by: Xiaoli Feng <xifeng@redhat.com>

diff --git a/fs/cifs/cifs_debug.c b/fs/cifs/cifs_debug.c
index e6025e9..ef93d60 100644 (file)
--- a/fs/cifs/cifs_debug.c
+++ b/fs/cifs/cifs_debug.c
@@ -584,6 +584,8 @@ static ssize_t cifsFYI_proc_write(struct file *file, const char __user *buffer,
                cifsFYI = bv;
        else if ((c[0] > '1') && (c[0] <= '9'))
                cifsFYI = (int) (c[0] - '0'); /* see cifs_debug.h for meanings */
+       else
+               return -EINVAL;
 
        return count;
 }