From patchwork Tue Oct 10 12:19:43 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Takashi Iwai X-Patchwork-Id: 9996011 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 2DDAC603B5 for ; Tue, 10 Oct 2017 12:29:12 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 218C32859A for ; Tue, 10 Oct 2017 12:29:12 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 16274285A2; Tue, 10 Oct 2017 12:29:12 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.9 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_NONE autolearn=unavailable version=3.3.1 Received: from alsa0.perex.cz (alsa0.perex.cz [77.48.224.243]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 214312859A for ; Tue, 10 Oct 2017 12:29:11 +0000 (UTC) Received: from alsa0.perex.cz (localhost [127.0.0.1]) by alsa0.perex.cz (Postfix) with ESMTP id 6C10C267354; Tue, 10 Oct 2017 14:19:50 +0200 (CEST) X-Original-To: alsa-devel@alsa-project.org Delivered-To: alsa-devel@alsa-project.org Received: by alsa0.perex.cz (Postfix, from userid 1000) id EEF4A267358; Tue, 10 Oct 2017 14:19:48 +0200 (CEST) Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by alsa0.perex.cz (Postfix) with ESMTP id 7A0EA266B38 for ; Tue, 10 Oct 2017 14:19:46 +0200 (CEST) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 52F3FAD19; Tue, 10 Oct 2017 12:19:45 +0000 (UTC) Date: Tue, 10 Oct 2017 14:19:43 +0200 Message-ID: From: Takashi Iwai To: Andrey Konovalov In-Reply-To: References: User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.8 Emacs/25.3 (x86_64-suse-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Cc: alsa-devel@alsa-project.org, Con Kolivas , LKML , Kostya Serebryany , syzkaller , Dmitry Vyukov , Stephen Barber , Bhumika Goyal Subject: Re: [alsa-devel] usb/sound: use-after-free in snd_usb_mixer_interrupt X-BeenThere: alsa-devel@alsa-project.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: alsa-devel-bounces@alsa-project.org X-Virus-Scanned: ClamAV using ClamSMTP On Tue, 10 Oct 2017 13:20:14 +0200, Andrey Konovalov wrote: > > On Tue, Oct 10, 2017 at 12:10 AM, Takashi Iwai wrote: > > On Mon, 09 Oct 2017 19:50:39 +0200, > > Andrey Konovalov wrote: > >> > >> Hi! > >> > >> I've got the following report while fuzzing the kernel with syzkaller. > >> > >> On commit 8a5776a5f49812d29fe4b2d0a2d71675c3facf3f (4.14-rc4). > >> > >> gadgetfs: bound to dummy_udc driver > >> usb 1-1: new full-speed USB device number 2 using dummy_hcd > >> gadgetfs: connected > >> gadgetfs: disconnected > >> gadgetfs: connected > >> usb 1-1: config 1 has an invalid interface number: 1 but max is 0 > >> usb 1-1: config 1 has 2 interfaces, different from the descriptor's value: 1 > >> usb 1-1: config 1 interface 0 altsetting 0 endpoint 0x81 has an > >> invalid bInterval 0, changing to 10 > >> usb 1-1: too many endpoints for config 1 interface 1 altsetting 174: > >> 131, using maximum allowed: 30 > >> usb 1-1: config 1 interface 1 altsetting 174 has 0 endpoint > >> descriptors, different from the interface de > >> scriptor's value: 131 > >> usb 1-1: config 1 interface 1 has no altsetting 0 > >> usb 1-1: New USB device found, idVendor=0dba, idProduct=1000 > >> usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=252 > >> usb 1-1: SerialNumber: a > >> gadgetfs: configuration #1 > >> hub 1-1:1.0: USB hub found > >> hub 1-1:1.0: config failed, can't read hub descriptor (err -22) > >> snd-usb-audio: probe of 1-1:1.0 failed with error -22 > >> ================================================================== > >> BUG: KASAN: use-after-free in snd_usb_mixer_interrupt+0x604/0x6f0 > >> Read of size 8 at addr ffff8800636f8900 by task swapper/1/0 > > > > A bad news for a sleepless night... > > > > It's a stray URB that isn't properly killed when the usb-audio mixer > > interface gets the error at probe. The patch below should fix it. > > I'm going to wrap up with a proper description later. > > This fixes the crash. > > Thanks! > > Tested-by: Andrey Konovalov Thanks, I'll queue the fix to for-linus branch. FWIW, below is the patch with the description. Takashi -- 8< -- From: Takashi Iwai Subject: [PATCH] ALSA: usb-audio: Kill stray URB at exiting 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: __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 Tested-by: Andrey Konovalov Cc: Signed-off-by: Takashi Iwai --- sound/usb/mixer.c | 12 ++++++++++-- sound/usb/mixer.h | 2 ++ 2 files changed, 12 insertions(+), 2 deletions(-) diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c index 9732edf77f86..91bc8f18791e 100644 --- a/sound/usb/mixer.c +++ b/sound/usb/mixer.c @@ -2234,6 +2234,9 @@ 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); @@ -2584,8 +2587,13 @@ int snd_usb_create_mixer(struct snd_usb_audio *chip, int ctrlif, 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 */