[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>
Cc: Greg KH <greg@kroah.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 11 insertions, 5 deletions

diff --git a/sound/core/control_compat.c b/sound/core/control_compat.c
index 418c6d4e5daf..a529b62972b4 100644
--- a/sound/core/control_compat.c
+++ b/sound/core/control_compat.c
@@ -167,7 +167,7 @@ static int get_ctl_type(struct snd_card *card, struct snd_ctl_elem_id *id,
                         int *countp)
 {
         struct snd_kcontrol *kctl;
-        struct snd_ctl_elem_info info;
+        struct snd_ctl_elem_info *info;
         int err;
 
         down_read(&card->controls_rwsem);
@@ -176,13 +176,19 @@ static int get_ctl_type(struct snd_card *card, struct snd_ctl_elem_id *id,
                 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;
 }