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 E13EAC43219 for ; Mon, 24 Jan 2022 19:18:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346895AbiAXTSO (ORCPT ); Mon, 24 Jan 2022 14:18:14 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46480 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346873AbiAXTIt (ORCPT ); Mon, 24 Jan 2022 14:08:49 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D5362C06118F; Mon, 24 Jan 2022 11:01:53 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 941ACB81215; Mon, 24 Jan 2022 19:01:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CA645C340E5; Mon, 24 Jan 2022 19:01:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1643050911; bh=xlYj8+vdIvrzfMuQbGn3srN8dLG2vTqYB47vCUgP9Qo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=d2Xk/Ejtqf+KG00nlV4ivS7fSja1uYMJtNJjRm/Ck7IiTiGW1rgMJ3uDtpZi+LFoX 7BBaVVzV3NAtj1ZOeZeKNeKu8j4WyZ8g6tDkid8ERZQbdhCeiNoA/BZoBCx2EIgKE3 b7/Q0aFY9VsEyQ17hvLeYJFkTgS8Bv/VZ0+KT3wE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Petr Cvachoucek , Richard Weinberger Subject: [PATCH 4.9 119/157] ubifs: Error path in ubifs_remount_rw() seems to wrongly free write buffers Date: Mon, 24 Jan 2022 19:43:29 +0100 Message-Id: <20220124183936.552565731@linuxfoundation.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220124183932.787526760@linuxfoundation.org> References: <20220124183932.787526760@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Petr Cvachoucek commit 3fea4d9d160186617ff40490ae01f4f4f36b28ff upstream. it seems freeing the write buffers in the error path of the ubifs_remount_rw() is wrong. It leads later to a kernel oops like this: [10016.431274] UBIFS (ubi0:0): start fixing up free space [10090.810042] UBIFS (ubi0:0): free space fixup complete [10090.814623] UBIFS error (ubi0:0 pid 512): ubifs_remount_fs: cannot spawn "ubifs_bgt0_0", error -4 [10101.915108] UBIFS (ubi0:0): background thread "ubifs_bgt0_0" started, PID 517 [10105.275498] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000030 [10105.284352] Mem abort info: [10105.287160] ESR = 0x96000006 [10105.290252] EC = 0x25: DABT (current EL), IL = 32 bits [10105.295592] SET = 0, FnV = 0 [10105.298652] EA = 0, S1PTW = 0 [10105.301848] Data abort info: [10105.304723] ISV = 0, ISS = 0x00000006 [10105.308573] CM = 0, WnR = 0 [10105.311564] user pgtable: 4k pages, 48-bit VAs, pgdp=00000000f03d1000 [10105.318034] [0000000000000030] pgd=00000000f6cee003, pud=00000000f4884003, pmd=0000000000000000 [10105.326783] Internal error: Oops: 96000006 [#1] PREEMPT SMP [10105.332355] Modules linked in: ath10k_pci ath10k_core ath mac80211 libarc4 cfg80211 nvme nvme_core cryptodev(O) [10105.342468] CPU: 3 PID: 518 Comm: touch Tainted: G O 5.4.3 #1 [10105.349517] Hardware name: HYPEX CPU (DT) [10105.353525] pstate: 40000005 (nZcv daif -PAN -UAO) [10105.358324] pc : atomic64_try_cmpxchg_acquire.constprop.22+0x8/0x34 [10105.364596] lr : mutex_lock+0x1c/0x34 [10105.368253] sp : ffff000075633aa0 [10105.371563] x29: ffff000075633aa0 x28: 0000000000000001 [10105.376874] x27: ffff000076fa80c8 x26: 0000000000000004 [10105.382185] x25: 0000000000000030 x24: 0000000000000000 [10105.387495] x23: 0000000000000000 x22: 0000000000000038 [10105.392807] x21: 000000000000000c x20: ffff000076fa80c8 [10105.398119] x19: ffff000076fa8000 x18: 0000000000000000 [10105.403429] x17: 0000000000000000 x16: 0000000000000000 [10105.408741] x15: 0000000000000000 x14: fefefefefefefeff [10105.414052] x13: 0000000000000000 x12: 0000000000000fe0 [10105.419364] x11: 0000000000000fe0 x10: ffff000076709020 [10105.424675] x9 : 0000000000000000 x8 : 00000000000000a0 [10105.429986] x7 : ffff000076fa80f4 x6 : 0000000000000030 [10105.435297] x5 : 0000000000000000 x4 : 0000000000000000 [10105.440609] x3 : 0000000000000000 x2 : ffff00006f276040 [10105.445920] x1 : ffff000075633ab8 x0 : 0000000000000030 [10105.451232] Call trace: [10105.453676] atomic64_try_cmpxchg_acquire.constprop.22+0x8/0x34 [10105.459600] ubifs_garbage_collect+0xb4/0x334 [10105.463956] ubifs_budget_space+0x398/0x458 [10105.468139] ubifs_create+0x50/0x180 [10105.471712] path_openat+0x6a0/0x9b0 [10105.475284] do_filp_open+0x34/0x7c [10105.478771] do_sys_open+0x78/0xe4 [10105.482170] __arm64_sys_openat+0x1c/0x24 [10105.486180] el0_svc_handler+0x84/0xc8 [10105.489928] el0_svc+0x8/0xc [10105.492808] Code: 52800013 17fffffb d2800003 f9800011 (c85ffc05) [10105.498903] ---[ end trace 46b721d93267a586 ]--- To reproduce the problem: 1. Filesystem initially mounted read-only, free space fixup flag set. 2. mount -o remount,rw 3. it takes some time (free space fixup running) ... try to terminate running mount by CTRL-C ... does not respond, only after free space fixup is complete ... then "ubifs_remount_fs: cannot spawn "ubifs_bgt0_0", error -4" 4. mount -o remount,rw ... now finished instantly (fixup already done). 5. Create file or just unmount the filesystem and we get the oops. Cc: Fixes: b50b9f408502 ("UBIFS: do not free write-buffers when in R/O mode") Signed-off-by: Petr Cvachoucek Signed-off-by: Richard Weinberger Signed-off-by: Greg Kroah-Hartman --- fs/ubifs/super.c | 1 - 1 file changed, 1 deletion(-) --- a/fs/ubifs/super.c +++ b/fs/ubifs/super.c @@ -1695,7 +1695,6 @@ out: kthread_stop(c->bgt); c->bgt = NULL; } - free_wbufs(c); kfree(c->write_reserve_buf); c->write_reserve_buf = NULL; vfree(c->ileb_buf);