Re: [PATCH] sound/usb: Fix memory leak in media_snd_stream_delete() during unbind

[Shuah Khan]

Adding Takashi Iwai

On 03/16/2016 08:58 PM, Shuah Khan wrote:
> media_snd_stream_delete() fails to release resources during unbind. This
> leads to use-after-free in media_gobj_create() on a subsequent bind.
> 
> [ 1445.086410] BUG: KASAN: use-after-free in media_gobj_create+0x3a1/0x470 [media] at addr ffff8801ead49998
> 
> [ 1445.086771] Call Trace:
> [ 1445.086779]  [<ffffffff81ade373>] dump_stack+0x67/0x94
> [ 1445.086785]  [<ffffffff81523c29>] print_trailer+0xf9/0x150
> [ 1445.086790]  [<ffffffff81529644>] object_err+0x34/0x40
> [ 1445.086796]  [<ffffffff8152b9e1>] kasan_report_error+0x221/0x530
> [ 1445.086803]  [<ffffffff8152bfb3>] __asan_report_store8_noabort+0x43/0x50
> [ 1445.086813]  [<ffffffffa0a79341>] ? media_gobj_create+0x3a1/0x470 [media]
> [ 1445.086822]  [<ffffffffa0a79341>] media_gobj_create+0x3a1/0x470 [media]
> [ 1445.086831]  [<ffffffffa0a705a9>] media_device_register_entity+0x259/0x6f0 [media]
> [ 1445.086841]  [<ffffffffa0a70350>] ? media_device_unregister_entity_notify+0x100/0x100 [media]
> [ 1445.086846]  [<ffffffff81526232>] ? ___slab_alloc+0x172/0x500
> [ 1445.086854]  [<ffffffff81203548>] ? mark_held_locks+0xc8/0x120
> [ 1445.086859]  [<ffffffff81526610>] ? __slab_alloc+0x50/0x70
> [ 1445.086878]  [<ffffffffa0fe711c>] ? media_snd_mixer_init+0x16c/0x500 [snd_usb_audio]
> [ 1445.086884]  [<ffffffff8152b086>] ? kasan_unpoison_shadow+0x36/0x50
> [ 1445.086890]  [<ffffffff8152b086>] ? kasan_unpoison_shadow+0x36/0x50
> [ 1445.086895]  [<ffffffff8152b0fe>] ? kasan_kmalloc+0x5e/0x70
> 
> Signed-off-by: Shuah Khan <shuahkh@xxxxxxxxxxxxxxx>
> ---
>  sound/usb/media.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/sound/usb/media.c b/sound/usb/media.c
> index 44a5de9..0d03773 100644
> --- a/sound/usb/media.c
> +++ b/sound/usb/media.c
> @@ -135,7 +135,7 @@ void media_snd_stream_delete(struct snd_usb_substream *subs)
>  	if (mctl && mctl->media_dev) {
>  		struct media_device *mdev;
>  
> -		mdev = subs->stream->chip->media_dev;
> +		mdev = mctl->media_dev;
>  		if (mdev && media_devnode_is_registered(&mdev->devnode)) {
>  			media_devnode_remove(mctl->intf_devnode);
>  			media_device_unregister_entity(&mctl->media_entity);
> 


-- 
Shuah Khan
Sr. Linux Kernel Developer
Open Source Innovation Group
Samsung Research America (Silicon Valley)
shuahkh@xxxxxxxxxxxxxxx | (970) 217-8978