unfuck sysfs_mount() (7b745a4e) · Commits · 戴 / test

new_sb is left uninitialized in case of early failures in kernfs_mount_ns(), and while IS_ERR(root) is true in all such cases, using IS_ERR(root) || !new_sb is not a solution - IS_ERR(root) is true in some cases when new_sb is true. Make sure new_sb is initialized (and matches the reality) in all cases and fix the condition for dropping kobj reference - we want it done precisely in those situations where the reference has not been transferred into a new super_block instance. Signed-off-by:

Al Viro <viro@zeniv.linux.org.uk>

fs/sysfs/mount.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -25,7 +25,7 @@ static struct dentry sysfs_mount(struct file_system_type fs_type,
		{
		struct dentry *root;
		void *ns;
		bool new_sb;
		bool new_sb = false;

		if (!(flags & SB_KERNMOUNT)) {
		if (!kobj_ns_current_may_mount(KOBJ_NS_TYPE_NET))
		@@ -35,9 +35,9 @@ static struct dentry sysfs_mount(struct file_system_type fs_type,
		ns = kobj_ns_grab_current(KOBJ_NS_TYPE_NET);
		root = kernfs_mount_ns(fs_type, flags, sysfs_root,
		SYSFS_MAGIC, &new_sb, ns);
		if (IS_ERR(root) \|\| !new_sb)
		if (!new_sb)
		kobj_ns_drop(KOBJ_NS_TYPE_NET, ns);
		else if (new_sb)
		else if (!IS_ERR(root))
		root->d_sb->s_iflags \|= SB_I_USERNS_VISIBLE;

		return root;

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