From patchwork Tue Jul 30 01:08:55 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chao Yu X-Patchwork-Id: 13746101 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 lists.sourceforge.net (lists.sourceforge.net [216.105.38.7]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C8936C3DA61 for ; Tue, 30 Jul 2024 01:09:14 +0000 (UTC) Received: from [127.0.0.1] (helo=sfs-ml-2.v29.lw.sourceforge.com) by sfs-ml-2.v29.lw.sourceforge.com with esmtp (Exim 4.95) (envelope-from ) id 1sYbMW-000449-Ir; Tue, 30 Jul 2024 01:09:12 +0000 Received: from [172.30.29.66] (helo=mx.sourceforge.net) by sfs-ml-2.v29.lw.sourceforge.com with esmtps (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1sYbMV-00043x-Ka for linux-f2fs-devel@lists.sourceforge.net; Tue, 30 Jul 2024 01:09:11 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sourceforge.net; s=x; h=Content-Transfer-Encoding:MIME-Version:Message-Id: Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:In-Reply-To:References:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=ON1v7D9jPPHD13SWlLJBlfahuekWa3rvOi5Wj4V/5as=; b=khiT/7ur6g1F0wUuqvAUlOWLvr BN6ba5r/NAQ/aH/c3y4ML7Fu+5rB46weTsX3Dmo1nwAPP8Brzilq25uobb0MBhLCGLg58QvxtR9yV VmQAEd85eUV0xSOnQzwa/ggwKjkxjMPsZmqHofiU5TKrdfcSZnMYJkw5uDX7sWR9m/fs=; DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sf.net; s=x ; h=Content-Transfer-Encoding:MIME-Version:Message-Id:Date:Subject:Cc:To:From :Sender:Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To: References:List-Id:List-Help:List-Unsubscribe:List-Subscribe:List-Post: List-Owner:List-Archive; bh=ON1v7D9jPPHD13SWlLJBlfahuekWa3rvOi5Wj4V/5as=; b=F 4dI+ZXPQ46xAs77ZSZLrvDZdbti1dH9fr7AuooUQHcJB85ghzd2g8Z17eykg+EJ3yVCsL3L91hrR9 m6OkbYVS/7qNK4qUNmunyvBvnVZ2Wiry8yw0COrZYDSzlX1qygnXgH0JpkdS1gb10ym2f2J2/JQLw UyxEeIlZAD5J/EcY=; Received: from sin.source.kernel.org ([145.40.73.55]) by sfi-mx-2.v28.lw.sourceforge.com with esmtps (TLS1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.95) id 1sYbMU-0006vU-IE for linux-f2fs-devel@lists.sourceforge.net; Tue, 30 Jul 2024 01:09:11 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sin.source.kernel.org (Postfix) with ESMTP id CDE24CE0138; Tue, 30 Jul 2024 01:09:03 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CF7C5C32786; Tue, 30 Jul 2024 01:09:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1722301743; bh=00h3vLXLvu9qJfB2DJPqbuEki7u3R/BDUL3XxZOien4=; h=From:To:Cc:Subject:Date:From; b=ob8XjfSqsHmR/KbOnkMZ94dCIyptHn0vixnagWEVhpi1pjUBfAdBT5EMWdA6yrs65 I/+cVdpEKzzE37HgOpcY9zDqkWFhCTVRFZN/S3v936R/0ThQRspibuVR1sPfRWsz15 Ejg4k8fbK32Fe8LLVNOCsrnRL/J692rHmhKXLDAF09UH9XzLqXRUqyRZnD6dX3rV8k VN1Wq/EpXRJyqhMYWcncykoSoJlJjmIdZlZbZG9WLT+3qpSdAzI/5eq2L2KhqiK0z4 e1pG4/pLH4nnFoU4ZSwUIBaKQ4NzKEPvQmVXw+ExfN8x4/+mM2G441Y4H3ecsANomE cFo7ZJITqrWQg== From: Chao Yu To: jaegeuk@kernel.org Date: Tue, 30 Jul 2024 09:08:55 +0800 Message-Id: <20240730010855.2942132-1-chao@kernel.org> X-Mailer: git-send-email 2.40.1 MIME-Version: 1.0 X-Headers-End: 1sYbMU-0006vU-IE Subject: [f2fs-dev] [PATCH v2] f2fs: fix to avoid use-after-free in f2fs_stop_gc_thread() X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: syzbot+1a8e2b31f2ac9bd3d148@syzkaller.appspotmail.com, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net syzbot reports a f2fs bug as below: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114 print_report+0xe8/0x550 mm/kasan/report.c:491 kasan_report+0x143/0x180 mm/kasan/report.c:601 kasan_check_range+0x282/0x290 mm/kasan/generic.c:189 instrument_atomic_read_write include/linux/instrumented.h:96 [inline] atomic_fetch_add_relaxed include/linux/atomic/atomic-instrumented.h:252 [inline] __refcount_add include/linux/refcount.h:184 [inline] __refcount_inc include/linux/refcount.h:241 [inline] refcount_inc include/linux/refcount.h:258 [inline] get_task_struct include/linux/sched/task.h:118 [inline] kthread_stop+0xca/0x630 kernel/kthread.c:704 f2fs_stop_gc_thread+0x65/0xb0 fs/f2fs/gc.c:210 f2fs_do_shutdown+0x192/0x540 fs/f2fs/file.c:2283 f2fs_ioc_shutdown fs/f2fs/file.c:2325 [inline] __f2fs_ioctl+0x443a/0xbe60 fs/f2fs/file.c:4325 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:907 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:893 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f The root cause is below race condition, it may cause use-after-free issue in sbi->gc_th pointer. - remount - f2fs_remount - f2fs_stop_gc_thread - kfree(gc_th) - f2fs_ioc_shutdown - f2fs_do_shutdown - f2fs_stop_gc_thread - kthread_stop(gc_th->f2fs_gc_task) : sbi->gc_thread = NULL; We will call f2fs_do_shutdown() in two paths: - for f2fs_ioc_shutdown() path, we should grab sb->s_umount semaphore for fixing. - for f2fs_shutdown() path, it's safe since caller has already grabbed sb->s_umount semaphore. Reported-by: syzbot+1a8e2b31f2ac9bd3d148@syzkaller.appspotmail.com Closes: https://lore.kernel.org/linux-f2fs-devel/0000000000005c7ccb061e032b9b@google.com Fixes: 7950e9ac638e ("f2fs: stop gc/discard thread after fs shutdown") Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim --- v2: - fix deadlock pointed out by Jaegeuk fs/f2fs/f2fs.h | 2 +- fs/f2fs/file.c | 11 +++++++++-- fs/f2fs/super.c | 2 +- 3 files changed, 11 insertions(+), 4 deletions(-) diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index 51fd5063a69c..0e0189084462 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -3508,7 +3508,7 @@ int f2fs_setattr(struct mnt_idmap *idmap, struct dentry *dentry, int f2fs_truncate_hole(struct inode *inode, pgoff_t pg_start, pgoff_t pg_end); void f2fs_truncate_data_blocks_range(struct dnode_of_data *dn, int count); int f2fs_do_shutdown(struct f2fs_sb_info *sbi, unsigned int flag, - bool readonly); + bool readonly, bool need_lock); int f2fs_precache_extents(struct inode *inode); int f2fs_fileattr_get(struct dentry *dentry, struct fileattr *fa); int f2fs_fileattr_set(struct mnt_idmap *idmap, diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c index 270c32e3385f..ac61c88f7688 100644 --- a/fs/f2fs/file.c +++ b/fs/f2fs/file.c @@ -2292,7 +2292,7 @@ static int f2fs_ioc_abort_atomic_write(struct file *filp) } int f2fs_do_shutdown(struct f2fs_sb_info *sbi, unsigned int flag, - bool readonly) + bool readonly, bool need_lock) { struct super_block *sb = sbi->sb; int ret = 0; @@ -2339,12 +2339,19 @@ int f2fs_do_shutdown(struct f2fs_sb_info *sbi, unsigned int flag, if (readonly) goto out; + /* grab sb->s_umount to avoid racing w/ remount() */ + if (need_lock) + down_read(&sbi->sb->s_umount); + f2fs_stop_gc_thread(sbi); f2fs_stop_discard_thread(sbi); f2fs_drop_discard_cmd(sbi); clear_opt(sbi, DISCARD); + if (need_lock) + up_read(&sbi->sb->s_umount); + f2fs_update_time(sbi, REQ_TIME); out: @@ -2381,7 +2388,7 @@ static int f2fs_ioc_shutdown(struct file *filp, unsigned long arg) } } - ret = f2fs_do_shutdown(sbi, in, readonly); + ret = f2fs_do_shutdown(sbi, in, readonly, true); if (need_drop) mnt_drop_write_file(filp); diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c index 4d2f3bb8e418..4a09dbb9fd54 100644 --- a/fs/f2fs/super.c +++ b/fs/f2fs/super.c @@ -2560,7 +2560,7 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data) static void f2fs_shutdown(struct super_block *sb) { - f2fs_do_shutdown(F2FS_SB(sb), F2FS_GOING_DOWN_NOSYNC, false); + f2fs_do_shutdown(F2FS_SB(sb), F2FS_GOING_DOWN_NOSYNC, false, false); } #ifdef CONFIG_QUOTA