• Takashi Iwai's avatar
    ALSA: usb-audio: Kill stray URB at exiting · 124751d5
    Takashi Iwai authored
    USB-audio driver may leave a stray URB for the mixer interrupt when it
    exits by some error during probe.  This leads to a use-after-free
    error as spotted by syzkaller like:
      ==================================================================
      BUG: KASAN: use-after-free in snd_usb_mixer_interrupt+0x604/0x6f0
      Call Trace:
       <IRQ>
       __dump_stack lib/dump_stack.c:16
       dump_stack+0x292/0x395 lib/dump_stack.c:52
       print_address_description+0x78/0x280 mm/kasan/report.c:252
       kasan_report_error mm/kasan/report.c:351
       kasan_report+0x23d/0x350 mm/kasan/report.c:409
       __asan_report_load8_noabort+0x19/0x20 mm/kasan/report.c:430
       snd_usb_mixer_interrupt+0x604/0x6f0 sound/usb/mixer.c:2490
       __usb_hcd_giveback_urb+0x2e0/0x650 drivers/usb/core/hcd.c:1779
       ....
    
      Allocated by task 1484:
       save_stack_trace+0x1b/0x20 arch/x86/kernel/stacktrace.c:59
       save_stack+0x43/0xd0 mm/kasan/kasan.c:447
       set_track mm/kasan/kasan.c:459
       kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551
       kmem_cache_alloc_trace+0x11e/0x2d0 mm/slub.c:2772
       kmalloc ./include/linux/slab.h:493
       kzalloc ./include/linux/slab.h:666
       snd_usb_create_mixer+0x145/0x1010 sound/usb/mixer.c:2540
       create_standard_mixer_quirk+0x58/0x80 sound/usb/quirks.c:516
       snd_usb_create_quirk+0x92/0x100 sound/usb/quirks.c:560
       create_composite_quirk+0x1c4/0x3e0 sound/usb/quirks.c:59
       snd_usb_create_quirk+0x92/0x100 sound/usb/quirks.c:560
       usb_audio_probe+0x1040/0x2c10 sound/usb/card.c:618
       ....
    
      Freed by task 1484:
       save_stack_trace+0x1b/0x20 arch/x86/kernel/stacktrace.c:59
       save_stack+0x43/0xd0 mm/kasan/kasan.c:447
       set_track mm/kasan/kasan.c:459
       kasan_slab_free+0x72/0xc0 mm/kasan/kasan.c:524
       slab_free_hook mm/slub.c:1390
       slab_free_freelist_hook mm/slub.c:1412
       slab_free mm/slub.c:2988
       kfree+0xf6/0x2f0 mm/slub.c:3919
       snd_usb_mixer_free+0x11a/0x160 sound/usb/mixer.c:2244
       snd_usb_mixer_dev_free+0x36/0x50 sound/usb/mixer.c:2250
       __snd_device_free+0x1ff/0x380 sound/core/device.c:91
       snd_device_free_all+0x8f/0xe0 sound/core/device.c:244
       snd_card_do_free sound/core/init.c:461
       release_card_device+0x47/0x170 sound/core/init.c:181
       device_release+0x13f/0x210 drivers/base/core.c:814
       ....
    
    Actually such a URB is killed properly at disconnection when the
    device gets probed successfully, and what we need is to apply it for
    the error-path, too.
    
    In this patch, we apply snd_usb_mixer_disconnect() at releasing.
    Also introduce a new flag, disconnected, to struct usb_mixer_interface
    for not performing the disconnection procedure twice.
    Reported-by: default avatarAndrey Konovalov <andreyknvl@google.com>
    Tested-by: default avatarAndrey Konovalov <andreyknvl@google.com>
    Cc: <stable@vger.kernel.org>
    Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
    124751d5
mixer.h 2.89 KB