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authorTakashi Iwai <tiwai@suse.de>2017-10-10 14:10:32 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-10-18 09:20:42 +0200
commitdc7c3bd09c7d2063c4d1be23d72ee85f1b3bb947 (patch)
treed4f8ca7300de7103ef325db7ffde9ba905fa47f5
parent050c4bbc09f17cc60363dabdda1c31aa36a66f1d (diff)
ALSA: usb-audio: Kill stray URB at exiting
commit 124751d5e63c823092060074bd0abaae61aaa9c4 upstream. 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: Andrey Konovalov <andreyknvl@google.com> Tested-by: Andrey Konovalov <andreyknvl@google.com> Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--sound/usb/mixer.c12
-rw-r--r--sound/usb/mixer.h2
2 files changed, 12 insertions, 2 deletions
diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index 696de5ac69be..a23efc8671d6 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -2161,6 +2161,9 @@ static int parse_audio_unit(struct mixer_build *state, int unitid)
static void snd_usb_mixer_free(struct usb_mixer_interface *mixer)
{
+ /* kill pending URBs */
+ snd_usb_mixer_disconnect(mixer);
+
kfree(mixer->id_elems);
if (mixer->urb) {
kfree(mixer->urb->transfer_buffer);
@@ -2504,8 +2507,13 @@ _error:
void snd_usb_mixer_disconnect(struct usb_mixer_interface *mixer)
{
- usb_kill_urb(mixer->urb);
- usb_kill_urb(mixer->rc_urb);
+ if (mixer->disconnected)
+ return;
+ if (mixer->urb)
+ usb_kill_urb(mixer->urb);
+ if (mixer->rc_urb)
+ usb_kill_urb(mixer->rc_urb);
+ mixer->disconnected = true;
}
#ifdef CONFIG_PM
diff --git a/sound/usb/mixer.h b/sound/usb/mixer.h
index 2b4b067646ab..545d99b09706 100644
--- a/sound/usb/mixer.h
+++ b/sound/usb/mixer.h
@@ -22,6 +22,8 @@ struct usb_mixer_interface {
struct urb *rc_urb;
struct usb_ctrlrequest *rc_setup_packet;
u8 rc_buffer[6];
+
+ bool disconnected;
};
#define MAX_CHANNELS 16 /* max logical channels */