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SubjectRe: stable-rc build: 9 warnings 0 failures (stable-rc/v3.18.75-20-g4ffe554)
On Tue, 17 Oct 2017 14:46:53 +0200,
Arnd Bergmann wrote:
>
> On Tue, Oct 17, 2017 at 12:22 PM, Olof's autobuilder <build@lixom.net> wrote:
> > Warnings:
> >
> > 9 sound/usb/mixer.c:2161:27: warning: passing argument 1 of 'snd_usb_mixer_disconnect' from incompatible pointer type [-Wincompatible-pointer-types]
>
> This broke after backporting 124751d5e63c ("ALSA: usb-audio: Kill stray
> URB at exiting") into linux-3.18.
>
> The interface was changed in commit a6cece9d8199 ("ALSA: usb-audio:
> Pass direct struct pointer instead of list_head"), which was merged in
> linux-3.19.
>
> I don't immediately see how this can be fixed. Backporting a6cece9d8199
> would probably work.

I already posted the revised patch yesterday, but apparently this
seems overlooked:

Subject: Re: [PATCH 3.18 08/19] ALSA: usb-audio: Kill stray URB at exiting
From: Takashi Iwai <tiwai@suse.de>
Date: Mon, 16 Oct 2017 20:50:02 +0200
Message-ID: <s5hpo9nylk5.wl-tiwai@suse.de>

The same patch is attached below.

Greg, could you replace the broken one?


thanks,

Takashi

-- 8< --
From: Takashi Iwai <tiwai@suse.de>
Subject: [PATCH 3.18.y] 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>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
sound/usb/mixer.c | 12 ++++++++++--
sound/usb/mixer.h | 1 +
2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index 1ceeb9e875a4..d0bbc7b32190 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -2157,6 +2157,9 @@ 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->list);
+
kfree(mixer->id_elems);
if (mixer->urb) {
kfree(mixer->urb->transfer_buffer);
@@ -2493,8 +2496,13 @@ void snd_usb_mixer_disconnect(struct list_head *p)
struct usb_mixer_interface *mixer;

mixer = list_entry(p, struct usb_mixer_interface, list);
- 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 73b1f649447b..cdff31de12d4 100644
--- a/sound/usb/mixer.h
+++ b/sound/usb/mixer.h
@@ -23,6 +23,7 @@ struct usb_mixer_interface {

u8 audigy2nx_leds[3];
u8 xonar_u1_status;
+ bool disconnected;
};

#define MAX_CHANNELS 16 /* max logical channels */
--
2.14.2
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