[PATCH] Fix snd-usb-audio in 32-bit compat environment

I'm getting oopses with snd-usb-audio in 32-bit compat environments:
control_compat.c:get_ctl_type() doesn't initialize 'info', so
'itemlist[uinfo->value.enumerated.item]' in
usbmixer.c:mixer_ctl_selector_info() might access random memory (The 'if
((int)uinfo->value.enumerated.item >= cval->max)' doesn't fix all problems
because of the unsigned -> signed conversion.)

Signed-off-by: Juergen Kreileder <jk@blackdown.de>
Cc: Jaroslav Kysela <perex@suse.cz>
Acked-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/sound/core/control_compat.c b/sound/core/control_compat.c
index 207c7de5129cba64c7ad340d7152352bb2a81973..6784528bb1a2ad822330d09a57e2a6e8a60128c3 100644 (file)
--- a/sound/core/control_compat.c
+++ b/sound/core/control_compat.c
@@ -164,7 +164,7 @@ struct sndrv_ctl_elem_value32 {
 static int get_ctl_type(snd_card_t *card, snd_ctl_elem_id_t *id, int *countp)
 {
        snd_kcontrol_t *kctl;
-       snd_ctl_elem_info_t info;
+       snd_ctl_elem_info_t *info;
        int err;
 
        down_read(&card->controls_rwsem);
@@ -173,13 +173,19 @@ static int get_ctl_type(snd_card_t *card, snd_ctl_elem_id_t *id, int *countp)
                up_read(&card->controls_rwsem);
                return -ENXIO;
        }
-       info.id = *id;
-       err = kctl->info(kctl, &info);
+       info = kzalloc(sizeof(*info), GFP_KERNEL);
+       if (info == NULL) {
+               up_read(&card->controls_rwsem);
+               return -ENOMEM;
+       }
+       info->id = *id;
+       err = kctl->info(kctl, info);
        up_read(&card->controls_rwsem);
        if (err >= 0) {
-               err = info.type;
-               *countp = info.count;
+               err = info->type;
+               *countp = info->count;
        }
+       kfree(info);
        return err;
 }