usb: core: Copy parameter string correctly and remove superfluous null check

BugLink: https://bugs.launchpad.net/bugs/1762695
strsep() slices string, so the string gets copied by
param_set_copystring() at the end of quirks_param_set() is not the
original value.
Fix that by calling param_set_copystring() earlier.

The null check for val is unnecessary, the caller of quirks_param_set()
does not pass null string.
Remove the superfluous null check. This is found by Smatch.

Fixes: 027bd6cafd9a ("usb: core: Add "quirks" parameter for usbcore")
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit a030501499b032bd218e1d01c07677bab6a0d53f)
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>

diff --git a/drivers/usb/core/quirks.c b/drivers/usb/core/quirks.c
index 6fb8d54332689a092eb5d24c87fc3bc7e2e0c37c..29e5f32b38df6b2f1e3969523ddb7160e2014f66 100644 (file)
--- a/drivers/usb/core/quirks.c
+++ b/drivers/usb/core/quirks.c
@@ -31,10 +31,15 @@ static int quirks_param_set(const char *val, const struct kernel_param *kp)
        u16 vid, pid;
        u32 flags;
        size_t i;
+       int err;
+
+       err = param_set_copystring(val, kp);
+       if (err)
+               return err;
 
        mutex_lock(&quirk_mutex);
 
-       if (!val || !*val) {
+       if (!*val) {
                quirk_count = 0;
                kfree(quirk_list);
                quirk_list = NULL;
@@ -133,7 +138,7 @@ static int quirks_param_set(const char *val, const struct kernel_param *kp)
 unlock:
        mutex_unlock(&quirk_mutex);
 
-       return param_set_copystring(val, kp);
+       return 0;
 }
 
 static const struct kernel_param_ops quirks_param_ops = {