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| author | Takashi Iwai <tiwai@suse.de> | 2017-09-12 12:41:20 +0200 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2017-09-12 12:41:20 +0200 |
| commit | fc27fe7e8deef2f37cba3f2be2d52b6ca5eb9d57 (patch) | |
| tree | 83115fdf1e49fd3069bbea5cb317011eda43f128 /sound | |
| parent | f16e666b9b7e07237ca0669df9b89ccf8dfc102c (diff) | |
| download | lwn-fc27fe7e8deef2f37cba3f2be2d52b6ca5eb9d57.tar.gz lwn-fc27fe7e8deef2f37cba3f2be2d52b6ca5eb9d57.zip | |
ALSA: seq: Cancel pending autoload work at unbinding device
ALSA sequencer core has a mechanism to load the enumerated devices
automatically, and it's performed in an off-load work. This seems
causing some race when a sequencer is removed while the pending
autoload work is running. As syzkaller spotted, it may lead to some
use-after-free:
BUG: KASAN: use-after-free in snd_rawmidi_dev_seq_free+0x69/0x70
sound/core/rawmidi.c:1617
Write of size 8 at addr ffff88006c611d90 by task kworker/2:1/567
CPU: 2 PID: 567 Comm: kworker/2:1 Not tainted 4.13.0+ #29
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Workqueue: events autoload_drivers
Call Trace:
__dump_stack lib/dump_stack.c:16 [inline]
dump_stack+0x192/0x22c lib/dump_stack.c:52
print_address_description+0x78/0x280 mm/kasan/report.c:252
kasan_report_error mm/kasan/report.c:351 [inline]
kasan_report+0x230/0x340 mm/kasan/report.c:409
__asan_report_store8_noabort+0x1c/0x20 mm/kasan/report.c:435
snd_rawmidi_dev_seq_free+0x69/0x70 sound/core/rawmidi.c:1617
snd_seq_dev_release+0x4f/0x70 sound/core/seq_device.c:192
device_release+0x13f/0x210 drivers/base/core.c:814
kobject_cleanup lib/kobject.c:648 [inline]
kobject_release lib/kobject.c:677 [inline]
kref_put include/linux/kref.h:70 [inline]
kobject_put+0x145/0x240 lib/kobject.c:694
put_device+0x25/0x30 drivers/base/core.c:1799
klist_devices_put+0x36/0x40 drivers/base/bus.c:827
klist_next+0x264/0x4a0 lib/klist.c:403
next_device drivers/base/bus.c:270 [inline]
bus_for_each_dev+0x17e/0x210 drivers/base/bus.c:312
autoload_drivers+0x3b/0x50 sound/core/seq_device.c:117
process_one_work+0x9fb/0x1570 kernel/workqueue.c:2097
worker_thread+0x1e4/0x1350 kernel/workqueue.c:2231
kthread+0x324/0x3f0 kernel/kthread.c:231
ret_from_fork+0x25/0x30 arch/x86/entry/entry_64.S:425
The fix is simply to assure canceling the autoload work at removing
the device.
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Tested-by: Andrey Konovalov <andreyknvl@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound')
| -rw-r--r-- | sound/core/seq_device.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/sound/core/seq_device.c b/sound/core/seq_device.c index c4acf17e9f5e..e40a2cba5002 100644 --- a/sound/core/seq_device.c +++ b/sound/core/seq_device.c @@ -148,8 +148,10 @@ void snd_seq_device_load_drivers(void) flush_work(&autoload_work); } EXPORT_SYMBOL(snd_seq_device_load_drivers); +#define cancel_autoload_drivers() cancel_work_sync(&autoload_work) #else #define queue_autoload_drivers() /* NOP */ +#define cancel_autoload_drivers() /* NOP */ #endif /* @@ -159,6 +161,7 @@ static int snd_seq_device_dev_free(struct snd_device *device) { struct snd_seq_device *dev = device->device_data; + cancel_autoload_drivers(); put_device(&dev->dev); return 0; } |