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From: Hillf Danton <hdanton@sina.com>
To: syzbot <syzbot+5d34cc6474499a5ff516@syzkaller.appspotmail.com>
Cc: linux-kernel@vger.kernel.org,
	syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] [ntfs3?] KASAN: slab-use-after-free Read in chrdev_open
Date: Wed, 29 May 2024 06:58:29 +0800
Message-Id: <20240528225829.2818-1-hdanton@sina.com>
In-Reply-To: <000000000000f386f90616fea5ef@google.com>
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#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git  master

--- x/fs/open.c
+++ y/fs/open.c
@@ -952,7 +952,13 @@ static int do_dentry_open(struct file *f
 	if (!open)
 		open = f->f_op->open;
 	if (open) {
+		struct super_block *sb = inode->i_sb;
+
+		error = -ENODEV;
+		if (!super_trylock_shared(sb))
+			goto cleanup_all;
 		error = open(inode, f);
+		up_read(&sb->s_umount);
 		if (error)
 			goto cleanup_all;
 	}
--- x/fs/super.c
+++ y/fs/super.c
@@ -503,6 +503,7 @@ void deactivate_super(struct super_block
 {
 	if (!atomic_add_unless(&s->s_active, -1, 1)) {
 		__super_lock_excl(s);
+		s->s_flags |= SB_DYING;
 		deactivate_locked_super(s);
 	}
 }
--