From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DC222C4321E for ; Fri, 2 Dec 2022 15:27:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233545AbiLBP1c (ORCPT ); Fri, 2 Dec 2022 10:27:32 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60528 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233627AbiLBP1Z (ORCPT ); Fri, 2 Dec 2022 10:27:25 -0500 Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9FC58D49E3 for ; Fri, 2 Dec 2022 07:27:23 -0800 (PST) Received: from gallifrey.ext.pengutronix.de ([2001:67c:670:201:5054:ff:fe8d:eefb] helo=bjornoya.blackshift.org) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1p17wW-0007eq-GS; Fri, 02 Dec 2022 16:27:12 +0100 Received: from pengutronix.de (unknown [IPv6:2a03:f580:87bc:d400:63a6:d4c5:22e2:f72a]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (prime256v1) server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) (Authenticated sender: mkl-all@blackshift.org) by smtp.blackshift.org (Postfix) with ESMTPSA id 1E2CB1317A1; Fri, 2 Dec 2022 15:27:10 +0000 (UTC) Date: Fri, 2 Dec 2022 16:27:01 +0100 From: Marc Kleine-Budde To: "Jiri Slaby (SUSE)" Cc: dario.binacchi@amarulasolutions.com, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, Richard Palethorpe , Petr Vorel , Wolfgang Grandegger , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , linux-can@vger.kernel.org, netdev@vger.kernel.org, stable@vger.kernel.org, Max Staudt Subject: Re: [PATCH] can: slcan: fix freed work crash Message-ID: <20221202152701.ewnillsqded7uby4@pengutronix.de> References: <20221201073426.17328-1-jirislaby@kernel.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="ojrs3pnyh3h6c3hc" Content-Disposition: inline In-Reply-To: <20221201073426.17328-1-jirislaby@kernel.org> X-SA-Exim-Connect-IP: 2001:67c:670:201:5054:ff:fe8d:eefb X-SA-Exim-Mail-From: mkl@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --ojrs3pnyh3h6c3hc Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 01.12.2022 08:34:26, Jiri Slaby (SUSE) wrote: > The LTP test pty03 is causing a crash in slcan: > BUG: kernel NULL pointer dereference, address: 0000000000000008 > #PF: supervisor read access in kernel mode > #PF: error_code(0x0000) - not-present page > PGD 0 P4D 0 > Oops: 0000 [#1] PREEMPT SMP NOPTI > CPU: 0 PID: 348 Comm: kworker/0:3 Not tainted 6.0.8-1-default #1 openSU= SE Tumbleweed 9d20364b934f5aab0a9bdf84e8f45cfdfae39dab > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.15.0-= 0-g2dd4b9b-rebuilt.opensuse.org 04/01/2014 > Workqueue: 0x0 (events) > RIP: 0010:process_one_work (/home/rich/kernel/linux/kernel/workqueue.c:= 706 /home/rich/kernel/linux/kernel/workqueue.c:2185) > Code: 49 89 ff 41 56 41 55 41 54 55 53 48 89 f3 48 83 ec 10 48 8b 06 48= 8b 6f 48 49 89 c4 45 30 e4 a8 04 b8 00 00 00 00 4c 0f 44 e0 <49> 8b 44 24 = 08 44 8b a8 00 01 00 00 41 83 e5 20 f6 45 10 04 75 0e > RSP: 0018:ffffaf7b40f47e98 EFLAGS: 00010046 > RAX: 0000000000000000 RBX: ffff9d644e1b8b48 RCX: ffff9d649e439968 > RDX: 00000000ffff8455 RSI: ffff9d644e1b8b48 RDI: ffff9d64764aa6c0 > RBP: ffff9d649e4335c0 R08: 0000000000000c00 R09: ffff9d64764aa734 > R10: 0000000000000007 R11: 0000000000000001 R12: 0000000000000000 > R13: ffff9d649e4335e8 R14: ffff9d64490da780 R15: ffff9d64764aa6c0 > FS: 0000000000000000(0000) GS:ffff9d649e400000(0000) knlGS:00000000000= 00000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000000000000008 CR3: 0000000036424000 CR4: 00000000000006f0 > Call Trace: > > worker_thread (/home/rich/kernel/linux/kernel/workqueue.c:2436) > kthread (/home/rich/kernel/linux/kernel/kthread.c:376) > ret_from_fork (/home/rich/kernel/linux/arch/x86/entry/entry_64.S:312) >=20 > Apparently, the slcan's tx_work is freed while being scheduled. While > slcan_netdev_close() (netdev side) calls flush_work(&sl->tx_work), > slcan_close() (tty side) does not. So when the netdev is never set UP, > but the tty is stuffed with bytes and forced to wakeup write, the work > is scheduled, but never flushed. >=20 > So add an additional flush_work() to slcan_close() to be sure the work > is flushed under all circumstances. >=20 > The Fixes commit below moved flush_work() from slcan_close() to > slcan_netdev_close(). What was the rationale behind it? Maybe we can > drop the one in slcan_netdev_close()? >=20 > I see the same pattern in can327. So it perhaps needs the very same fix. >=20 > Fixes: cfcb4465e992 ("can: slcan: remove legacy infrastructure") > Link: https://bugzilla.suse.com/show_bug.cgi?id=3D1205597 > Reported-by: Richard Palethorpe > Tested-by: Petr Vorel > Cc: Dario Binacchi > Cc: Wolfgang Grandegger > Cc: Marc Kleine-Budde > Cc: "David S. Miller" > Cc: Eric Dumazet > Cc: Jakub Kicinski > Cc: Paolo Abeni > Cc: linux-can@vger.kernel.org > Cc: netdev@vger.kernel.org > Cc: stable@vger.kernel.org > Cc: Max Staudt > Signed-off-by: Jiri Slaby (SUSE) Added to linux-can, Thanks, Marc --=20 Pengutronix e.K. | Marc Kleine-Budde | Embedded Linux | https://www.pengutronix.de | Vertretung West/Dortmund | Phone: +49-231-2826-924 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | --ojrs3pnyh3h6c3hc Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEBsvAIBsPu6mG7thcrX5LkNig010FAmOKGUMACgkQrX5LkNig 011wWQgAn+U91/ZltYGvoyP6wurNPczrfH4QqhMQ3x77TXxYpIO7Bme9LzWgnowK aCZGAi6RhnBCwVHYrRkPuQ9karVWhlrEYkLRKZJcBG3fbbOFMC+lUy51Tk4Dd+fR GZKwdr4ODTxerh5E6PBqCais4zGBdzBqGB+md9C7EUnvgC5MeGSAf8EFUkRrmb8T Wd8F2IRz5FCOZ0JjlTDHWWoS4dedoiodLUhyDCXn2mDMVjtDGkCHcvMM+3MO1bE1 GLU21H65XDHg6nVBDmvMpLdfbvDxc3qVroe3wXyeJ8wzSd/acELrHusTZXKvmDg+ IU0m+hpBwzplYQLMJSzmk5zZN76bWQ== =XIQ/ -----END PGP SIGNATURE----- --ojrs3pnyh3h6c3hc--