[PATCH next 1/2] sound: usb: fix NULL ptr dereference in usb_audio_probe

[Takashi Iwai]

On Mon, 08 Mar 2021 23:30:36 +0100,
Pavel Skripkin wrote:
> 
> syzbot reported null pointer dereference in usb_audio_probe.
> The problem was in case, when quirk == NULL. It's not an
> error condition, so quirk must be checked before dereferencing.
> 
> Call Trace:
>  usb_probe_interface+0x315/0x7f0 drivers/usb/core/driver.c:396
>  really_probe+0x291/0xe60 drivers/base/dd.c:554
>  driver_probe_device+0x26b/0x3d0 drivers/base/dd.c:740
>  __device_attach_driver+0x1d1/0x290 drivers/base/dd.c:846
>  bus_for_each_drv+0x15f/0x1e0 drivers/base/bus.c:431
>  __device_attach+0x228/0x4a0 drivers/base/dd.c:914
>  bus_probe_device+0x1e4/0x290 drivers/base/bus.c:491
>  device_add+0xbdb/0x1db0 drivers/base/core.c:3242
>  usb_set_configuration+0x113f/0x1910 drivers/usb/core/message.c:2164
>  usb_generic_driver_probe+0xba/0x100 drivers/usb/core/generic.c:238
>  usb_probe_device+0xd9/0x2c0 drivers/usb/core/driver.c:293
>  really_probe+0x291/0xe60 drivers/base/dd.c:554
>  driver_probe_device+0x26b/0x3d0 drivers/base/dd.c:740
>  __device_attach_driver+0x1d1/0x290 drivers/base/dd.c:846
>  bus_for_each_drv+0x15f/0x1e0 drivers/base/bus.c:431
>  __device_attach+0x228/0x4a0 drivers/base/dd.c:914
>  bus_probe_device+0x1e4/0x290 drivers/base/bus.c:491
>  device_add+0xbdb/0x1db0 drivers/base/core.c:3242
>  usb_new_device.cold+0x721/0x1058 drivers/usb/core/hub.c:2555
>  hub_port_connect drivers/usb/core/hub.c:5223 [inline]
>  hub_port_connect_change drivers/usb/core/hub.c:5363 [inline]
>  port_event drivers/usb/core/hub.c:5509 [inline]
>  hub_event+0x2357/0x4320 drivers/usb/core/hub.c:5591
>  process_one_work+0x98d/0x1600 kernel/workqueue.c:2275
>  worker_thread+0x64c/0x1120 kernel/workqueue.c:2421
>  kthread+0x3b1/0x4a0 kernel/kthread.c:292
>  ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
> 
> Reported-by: syzbot+719da9b149a931f5143f at syzkaller.appspotmail.com
> Fixes: 9799110825db ("ALSA: usb-audio: Disable USB autosuspend properly in setup_disable_autosuspend()")
> Signed-off-by: Pavel Skripkin <paskripkin at gmail.com>

Thanks, applied now.


Takashi