Hi,
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.)
Here's a fix:
Signed-off-by: Juergen Kreileder <[email protected]>
--- linux-mm-vanilla/sound/core/control_compat.c 2006-02-18 17:00:17.000000000 +0100
+++ linux-mm/sound/core/control_compat.c 2006-02-18 19:17:45.000000000 +0100
@@ -167,7 +167,7 @@ static int get_ctl_type(struct snd_card
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
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;
}
=
Tested on ppc64.
Juergen
--
Juergen Kreileder, Blackdown Java-Linux Team
http://blog.blackdown.de/
On Sat, Feb 18, 2006 at 07:50:37PM +0100, Juergen Kreileder wrote:
> 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.)
IMO, what you did is an overkill. Does this patch fixes your problem?
Signed-off-by: Alexey Dobriyan <[email protected]>
--- a/sound/core/control_compat.c
+++ b/sound/core/control_compat.c
@@ -176,6 +176,7 @@ static int get_ctl_type(struct snd_card
up_read(&card->controls_rwsem);
return -ENXIO;
}
+ memset(info, 0, sizeof(struct snd_ctl_elem_info));
info.id = *id;
err = kctl->info(kctl, &info);
up_read(&card->controls_rwsem);
> --- linux-mm-vanilla/sound/core/control_compat.c
> +++ linux-mm/sound/core/control_compat.c
> @@ -167,7 +167,7 @@ static int get_ctl_type(struct snd_card
> 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
> 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;
> }
Alexey Dobriyan <[email protected]> writes:
> On Sat, Feb 18, 2006 at 07:50:37PM +0100, Juergen Kreileder wrote:
>> 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.)
>
> IMO, what you did is an overkill.
The advantage of the longer fix is reduced stack usage.
> Does this patch fixes your problem?
Yes but you can have that even simpler:
--- linux-mm-vanilla/sound/core/control_compat.c 2006-02-18 17:00:17.000000000 +0100
+++ linux-mm/sound/core/control_compat.c 2006-02-19 19:41:51.000000000 +0100
@@ -167,7 +167,7 @@ static int get_ctl_type(struct snd_card
int *countp)
{
struct snd_kcontrol *kctl;
- struct snd_ctl_elem_info info;
+ struct snd_ctl_elem_info info = {0};
int err;
down_read(&card->controls_rwsem);
=
Juergen
--
Juergen Kreileder, Blackdown Java-Linux Team
http://blog.blackdown.de/
At Sun, 19 Feb 2006 20:02:03 +0100,
Juergen Kreileder wrote:
>
> Alexey Dobriyan <[email protected]> writes:
>
> > On Sat, Feb 18, 2006 at 07:50:37PM +0100, Juergen Kreileder wrote:
> >> 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.)
> >
> > IMO, what you did is an overkill.
>
> The advantage of the longer fix is reduced stack usage.
But it also introduces a kmalloc overhead.
Let's fix the problem first with a simpler patch.
> > Does this patch fixes your problem?
>
> Yes but you can have that even simpler:
>
> --- linux-mm-vanilla/sound/core/control_compat.c 2006-02-18 17:00:17.000000000 +0100
> +++ linux-mm/sound/core/control_compat.c 2006-02-19 19:41:51.000000000 +0100
> @@ -167,7 +167,7 @@ static int get_ctl_type(struct snd_card
> int *countp)
> {
> struct snd_kcontrol *kctl;
> - struct snd_ctl_elem_info info;
> + struct snd_ctl_elem_info info = {0};
> int err;
>
> down_read(&card->controls_rwsem);
I prefer Alexey's patch sicne it's clearer that the
zero-initialization is done just before the usage.
But = {0} might result in a better code because of compiler
optimization...
Thanks!
Takashi