From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B6E481863 for ; Wed, 28 Dec 2022 15:17:37 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 38D97C433EF; Wed, 28 Dec 2022 15:17:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1672240657; bh=PcfMU0DyL2GxuhDzcuqKtUnt5H43hy3OifcxGBCv+hQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Ch3VZibaJGX6/Ywa4VaPvDYLw/0S1NRQyNzWO4XPzLJjxSQmhQjtG/0Dd08ZFnLNp xop7Pjl9V+pxlavn1nl9iFJQLbPDu6V6oO3lS0Wr00t7bCgn/zz1NJshJsNCw64fjj u1y6TxEScOJ/psiBorqClo4KfeoQnDCNXzwpqTBA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+035a381ea1afb63f098d@syzkaller.appspotmail.com, syzbot+729c925c2d9fc495ddee@syzkaller.appspotmail.com, Chao Yu , Jaegeuk Kim , Sasha Levin Subject: [PATCH 5.15 378/731] f2fs: fix to invalidate dcc->f2fs_issue_discard in error path Date: Wed, 28 Dec 2022 15:38:05 +0100 Message-Id: <20221228144307.518864039@linuxfoundation.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20221228144256.536395940@linuxfoundation.org> References: <20221228144256.536395940@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Chao Yu [ Upstream commit 91586ce0d39a05f88795aa8814fb99b1387236b3 ] Syzbot reports a NULL pointer dereference issue as below: __refcount_add include/linux/refcount.h:193 [inline] __refcount_inc include/linux/refcount.h:250 [inline] refcount_inc include/linux/refcount.h:267 [inline] get_task_struct include/linux/sched/task.h:110 [inline] kthread_stop+0x34/0x1c0 kernel/kthread.c:703 f2fs_stop_discard_thread+0x3c/0x5c fs/f2fs/segment.c:1638 kill_f2fs_super+0x5c/0x194 fs/f2fs/super.c:4522 deactivate_locked_super+0x70/0xe8 fs/super.c:332 deactivate_super+0xd0/0xd4 fs/super.c:363 cleanup_mnt+0x1f8/0x234 fs/namespace.c:1186 __cleanup_mnt+0x20/0x30 fs/namespace.c:1193 task_work_run+0xc4/0x14c kernel/task_work.c:177 exit_task_work include/linux/task_work.h:38 [inline] do_exit+0x26c/0xbe0 kernel/exit.c:795 do_group_exit+0x60/0xe8 kernel/exit.c:925 __do_sys_exit_group kernel/exit.c:936 [inline] __se_sys_exit_group kernel/exit.c:934 [inline] __wake_up_parent+0x0/0x40 kernel/exit.c:934 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall arch/arm64/kernel/syscall.c:52 [inline] el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x48/0x164 arch/arm64/kernel/syscall.c:206 el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:636 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:654 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581 The root cause of this issue is in error path of f2fs_start_discard_thread(), it missed to invalidate dcc->f2fs_issue_discard, later kthread_stop() may access invalid pointer. Fixes: 4d67490498ac ("f2fs: Don't create discard thread when device doesn't support realtime discard") Reported-by: syzbot+035a381ea1afb63f098d@syzkaller.appspotmail.com Reported-by: syzbot+729c925c2d9fc495ddee@syzkaller.appspotmail.com Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim Signed-off-by: Sasha Levin --- fs/f2fs/segment.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c index af810b2d5d90..28939e3573ea 100644 --- a/fs/f2fs/segment.c +++ b/fs/f2fs/segment.c @@ -2129,8 +2129,10 @@ int f2fs_start_discard_thread(struct f2fs_sb_info *sbi) dcc->f2fs_issue_discard = kthread_run(issue_discard_thread, sbi, "f2fs_discard-%u:%u", MAJOR(dev), MINOR(dev)); - if (IS_ERR(dcc->f2fs_issue_discard)) + if (IS_ERR(dcc->f2fs_issue_discard)) { err = PTR_ERR(dcc->f2fs_issue_discard); + dcc->f2fs_issue_discard = NULL; + } return err; } -- 2.35.1