From patchwork Wed Sep 4 15:54:20 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alan Stern X-Patchwork-Id: 11130959 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id CE1701398 for ; Wed, 4 Sep 2019 15:54:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B900C233FF for ; Wed, 4 Sep 2019 15:54:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731233AbfIDPyV (ORCPT ); Wed, 4 Sep 2019 11:54:21 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:47120 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1731512AbfIDPyV (ORCPT ); Wed, 4 Sep 2019 11:54:21 -0400 Received: (qmail 4989 invoked by uid 2102); 4 Sep 2019 11:54:20 -0400 Received: from localhost (sendmail-bs@127.0.0.1) by localhost with SMTP; 4 Sep 2019 11:54:20 -0400 Date: Wed, 4 Sep 2019 11:54:20 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Jiri Kosina cc: andreyknvl@google.com, , , Kernel development list , USB list , Subject: [PATCH] HID: hid-prodikeys: Fix general protection fault during probe In-Reply-To: <0000000000002725f40591a4f118@google.com> Message-ID: MIME-Version: 1.0 Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org The syzbot fuzzer provoked a general protection fault in the hid-prodikeys driver: 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: 0 PID: 12 Comm: kworker/0:1 Not tainted 5.3.0-rc5+ #28 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: usb_hub_wq hub_event RIP: 0010:pcmidi_submit_output_report drivers/hid/hid-prodikeys.c:300 [inline] RIP: 0010:pcmidi_set_operational drivers/hid/hid-prodikeys.c:558 [inline] RIP: 0010:pcmidi_snd_initialise drivers/hid/hid-prodikeys.c:686 [inline] RIP: 0010:pk_probe+0xb51/0xfd0 drivers/hid/hid-prodikeys.c:836 Code: 0f 85 50 04 00 00 48 8b 04 24 4c 89 7d 10 48 8b 58 08 e8 b2 53 e4 fc 48 8b 54 24 20 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <80> 3c 02 00 0f 85 13 04 00 00 48 ba 00 00 00 00 00 fc ff df 49 8b The problem is caused by the fact that pcmidi_get_output_report() will return an error if the HID device doesn't provide the right sort of output report, but pcmidi_set_operational() doesn't bother to check the return code and assumes the function call always succeeds. This patch adds the missing check and aborts the probe operation if necessary. Reported-and-tested-by: syzbot+1088533649dafa1c9004@syzkaller.appspotmail.com Signed-off-by: Alan Stern CC: --- [as1911] drivers/hid/hid-prodikeys.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) Index: usb-devel/drivers/hid/hid-prodikeys.c =================================================================== --- usb-devel.orig/drivers/hid/hid-prodikeys.c +++ usb-devel/drivers/hid/hid-prodikeys.c @@ -551,10 +551,14 @@ static void pcmidi_setup_extra_keys( static int pcmidi_set_operational(struct pcmidi_snd *pm) { + int rc; + if (pm->ifnum != 1) return 0; /* only set up ONCE for interace 1 */ - pcmidi_get_output_report(pm); + rc = pcmidi_get_output_report(pm); + if (rc < 0) + return rc; pcmidi_submit_output_report(pm, 0xc1); return 0; } @@ -683,7 +687,11 @@ static int pcmidi_snd_initialise(struct spin_lock_init(&pm->rawmidi_in_lock); init_sustain_timers(pm); - pcmidi_set_operational(pm); + err = pcmidi_set_operational(pm); + if (err < 0) { + pk_error("failed to find output report\n"); + goto fail_register; + } /* register it */ err = snd_card_register(card);