[PATCH] ALSA: usb-audio: fix a memory leak bug

[Wenwen Wang <wenwen@cs.uga.edu>]

In add_new_ctl(), a mixer element structure is allocated through kzalloc()
and the pointer is saved to 'elem'. Later on, a new alsa control element is
created and added to this structure. In case the add process fails, i.e.,
the return value of snd_usb_mixer_add_control() is less than 0, the
allocated structure is not freed, leading to a memory leak.

To fix the above issue, free 'elem' before returning the error.

Signed-off-by: Wenwen Wang <wenwen@cs.uga.edu>
---
 sound/usb/mixer_scarlett.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/sound/usb/mixer_scarlett.c b/sound/usb/mixer_scarlett.c
index 83715fd..a6c028a 100644
--- a/sound/usb/mixer_scarlett.c
+++ b/sound/usb/mixer_scarlett.c
@@ -562,8 +562,10 @@ static int add_new_ctl(struct usb_mixer_interface *mixer,
        strlcpy(kctl->id.name, name, sizeof(kctl->id.name));

        err = snd_usb_mixer_add_control(&elem->head, kctl);
-       if (err < 0)
+       if (err < 0) {
+               kfree(elem);
                return err;
+       }

        if (elem_ret)
                *elem_ret = elem;
--
2.7.4