On Wed, Jul 24, 2019 at 3:15 PM Takashi Iwai <tiwai@xxxxxxx> wrote: > > On Tue, 23 Jul 2019 19:03:29 +0200, > Andrey Konovalov wrote: > > > > (Takashi, with your helper check syzkaller now generates a new bug > > report (not reported by syzbot yet due to breakage during kernel boot > > on 5.3-rc1, so see below) and I guess this has to do with a missing ep > > != NULL check). > > > > kasan: CONFIG_KASAN_INLINE enabled > > kasan: GPF could be caused by NULL-ptr deref or user memory access > > general protection fault: 0000 [#1] SMP KASAN > > CPU: 1 PID: 74 Comm: kworker/1:1 Not tainted 5.3.0-rc1+ #40 > > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 > > Workqueue: usb_hub_wq hub_event > > RIP: 0010:snd_usb_pipe_sanity_check+0x80/0x130 sound/usb/helper.c:75 > > Code: 48 c1 ea 03 80 3c 02 00 0f 85 b3 00 00 00 48 8b 6d 00 c1 eb 1e > > 48 b8 00 00 00 00 00 fc ff df 48 8d 7d 03 48 89 fa 48 c1 ea 03 <0f> b6 > > 04 02 48 89 fa 83 e2 07 38 d0 7f 04 84 c0 75 7b 48 b8 00 00 > > RSP: 0018:ffff88806c33f0a8 EFLAGS: 00010246 > > RAX: dffffc0000000000 RBX: 0000000000000001 RCX: ffffffff833819c2 > > RDX: 0000000000000000 RSI: ffffffff833819dc RDI: 0000000000000003 > > RBP: 0000000000000000 R08: ffff88806c330000 R09: fffffbfff0d1a792 > > R10: fffffbfff0d1a791 R11: ffffffff868d3c8f R12: 0000000000000000 > > R13: dffffc0000000000 R14: ffff88806975cc80 R15: ffff88806975c4a0 > > FS: 0000000000000000(0000) GS:ffff88806d100000(0000) knlGS:0000000000000000 > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > CR2: 00007fcc3a48c000 CR3: 000000006861c003 CR4: 0000000000160ee0 > > Call Trace: > > snd_usb_accessmusic_boot_quirk sound/usb/quirks.c:835 [inline] > > snd_usb_apply_boot_quirk+0xa19/0xc60 sound/usb/quirks.c:1267 > > usb_audio_probe+0x2ec/0x1f40 sound/usb/card.c:576 > (snip) > > So it's a NULL pointer returned from usb_pipe_endpoint() with an > invalid pipe. The fix patch is attached below. Thanks for the fix! Do you think it makes sense to reuse the already existing usb_urb_ep_type_check() function instead of snd_usb_pipe_sanity_check() as Hillf suggested? They seem to be doing essentially the same thing. > > > thanks, > > Takashi > > -- 8< -- > From: Takashi Iwai <tiwai@xxxxxxx> > Subject: [PATCH] ALSA: usb-audio: Fix NULL dereference at pipe sanity check > > The newly introduced helper for a sanity check of a pipe causes an > Oops due to the NULL pointer returned from usb_pipe_endpoint() with an > invalid pipe. Let's fix it. > > Fixes: 801ebf1043ae ("ALSA: usb-audio: Sanity checks for each pipe and EP types") > Reported-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx> > Signed-off-by: Takashi Iwai <tiwai@xxxxxxx> > --- > sound/usb/helper.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/sound/usb/helper.c b/sound/usb/helper.c > index 71d5f540334a..919d69e0aba3 100644 > --- a/sound/usb/helper.c > +++ b/sound/usb/helper.c > @@ -72,6 +72,8 @@ int snd_usb_pipe_sanity_check(struct usb_device *dev, unsigned int pipe) > struct usb_host_endpoint *ep; > > ep = usb_pipe_endpoint(dev, pipe); > + if (!ep) > + return -EINVAL; > if (usb_pipetype(pipe) != pipetypes[usb_endpoint_type(&ep->desc)]) > return -EINVAL; > return 0; > -- > 2.16.4 > > -- > You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group. > To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@xxxxxxxxxxxxxxxx. > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/s5hlfwn376e.wl-tiwai%40suse.de.