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 57CFEEB64D9 for ; Fri, 16 Jun 2023 02:00:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239804AbjFPCAq (ORCPT ); Thu, 15 Jun 2023 22:00:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36730 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236191AbjFPCAp (ORCPT ); Thu, 15 Jun 2023 22:00:45 -0400 Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 34CA62D55 for ; Thu, 15 Jun 2023 19:00:30 -0700 (PDT) Received: from mail02.huawei.com (unknown [172.30.67.153]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTP id 4Qj2Rt0t6Nz4f3jJF for ; Fri, 16 Jun 2023 10:00:26 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.104.67]) by APP4 (Coremail) with SMTP id gCh0CgCHK583wotk1M05Lw--.53637S4; Fri, 16 Jun 2023 10:00:26 +0800 (CST) From: Zhang Yi To: linux-ext4@vger.kernel.org Cc: tytso@mit.edu, adilger.kernel@dilger.ca, jack@suse.cz, yi.zhang@huawei.com, yi.zhang@huaweicloud.com, chengzhihao1@huawei.com, yukuai3@huawei.com Subject: [PATCH v2] jbd2: skip reading super block if it has been verified Date: Fri, 16 Jun 2023 09:55:47 +0800 Message-Id: <20230616015547.3155195-1-yi.zhang@huaweicloud.com> X-Mailer: git-send-email 2.39.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID: gCh0CgCHK583wotk1M05Lw--.53637S4 X-Coremail-Antispam: 1UD129KBjvJXoWxAw45try5uF1kWrW7Jry8Grg_yoW5AFy5pr y3KFy8urWvvr15Aa18tFs7CFWUWay0yFyUGrn7uwn2yay8Xrnrtr9rKr15JF90yFW8Wa48 tF4DKa9akw4qkwUanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUyG14x267AKxVW8JVW5JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26w1j6s0DM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26r4U JVWxJr1l84ACjcxK6I8E87Iv67AKxVW0oVCq3wA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_Gc CE3s1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2WlYx0E 2Ix0cI8IcVAFwI0_JrI_JrylYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkEbVWUJV W8JwACjcxG0xvY0x0EwIxGrwACjI8F5VA0II8E6IAqYI8I648v4I1l42xK82IYc2Ij64vI r41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x8Gjc xK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r1q6r43MIIYrxkI7VAKI48JMIIF0xvE2Ix0 cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E14v26r1j6r4UMIIF0xvE42xK8V AvwI8IcIk0rVWrZr1j6s0DMIIF0xvEx4A2jsIE14v26r1j6r4UMIIF0xvEx4A2jsIEc7Cj xVAFwI0_Jr0_GrUvcSsGvfC2KfnxnUUI43ZEXa7VU1a9aPUUUUU== X-CM-SenderInfo: d1lo6xhdqjqx5xdzvxpfor3voofrz/ X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org From: Zhang Yi We got a NULL pointer dereference issue below while running generic/475 I/O failure pressure test. BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 0 P4D 0 Oops: 0002 [#1] PREEMPT SMP PTI CPU: 1 PID: 15600 Comm: fsstress Not tainted 6.4.0-rc5-xfstests-00055-gd3ab1bca26b4 #190 RIP: 0010:jbd2_journal_set_features+0x13d/0x430 ... Call Trace: ? __die+0x23/0x60 ? page_fault_oops+0xa4/0x170 ? exc_page_fault+0x67/0x170 ? asm_exc_page_fault+0x26/0x30 ? jbd2_journal_set_features+0x13d/0x430 jbd2_journal_revoke+0x47/0x1e0 __ext4_forget+0xc3/0x1b0 ext4_free_blocks+0x214/0x2f0 ext4_free_branches+0xeb/0x270 ext4_ind_truncate+0x2bf/0x320 ext4_truncate+0x1e4/0x490 ext4_handle_inode_extension+0x1bd/0x2a0 ? iomap_dio_complete+0xaf/0x1d0 The root cause is the journal super block had been failed to write out due to I/O fault injection, it's uptodate bit was cleared by end_buffer_write_sync() and didn't reset yet in jbd2_write_superblock(). And it raced by journal_get_superblock()->bh_read(), unfortunately, the read IO is also failed, so the error handling in journal_fail_superblock() unexpectedly clear the journal->j_sb_buffer, finally lead to above NULL pointer dereference issue. If the journal super block had been read and verified, there is no need to call bh_read() read it again even if it has been failed to written out. So the fix could be simply move buffer_verified(bh) in front of bh_read(). Also remove a stale comment left in jbd2_journal_check_used_features(). Fixes: 51bacdba23d8 ("jbd2: factor out journal initialization from journal_get_superblock()") Reported-by: Theodore Ts'o Signed-off-by: Zhang Yi --- v1->v2: - Remove a stale comment left in jbd2_journal_check_used_features(). fs/jbd2/journal.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c index b5e57735ab3f..559242df0f9a 100644 --- a/fs/jbd2/journal.c +++ b/fs/jbd2/journal.c @@ -1919,6 +1919,9 @@ static int journal_get_superblock(journal_t *journal) bh = journal->j_sb_buffer; J_ASSERT(bh != NULL); + if (buffer_verified(bh)) + return 0; + err = bh_read(bh, 0); if (err < 0) { printk(KERN_ERR @@ -1926,9 +1929,6 @@ static int journal_get_superblock(journal_t *journal) goto out; } - if (buffer_verified(bh)) - return 0; - sb = journal->j_superblock; err = -EINVAL; @@ -2229,7 +2229,6 @@ int jbd2_journal_check_used_features(journal_t *journal, unsigned long compat, if (!compat && !ro && !incompat) return 1; - /* Load journal superblock if it is not loaded yet. */ if (journal_get_superblock(journal)) return 0; if (!jbd2_format_support_feature(journal)) -- 2.39.2