This is a note to let you know that I've just added the patch titled unfuck sysfs_mount() to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: unfuck-sysfs_mount.patch and it can be found in the queue-4.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 7b745a4e4051e1bbce40e0b1c2cf636c70583aa4 Mon Sep 17 00:00:00 2001 From: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Date: Mon, 14 May 2018 00:03:34 -0400 Subject: unfuck sysfs_mount() From: Al Viro <viro@xxxxxxxxxxxxxxxxxx> commit 7b745a4e4051e1bbce40e0b1c2cf636c70583aa4 upstream. 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@xxxxxxxxxxxxxxxxxx> Signed-off-by: Guilherme G. Piccoli <gpiccoli@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/sysfs/mount.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/fs/sysfs/mount.c +++ b/fs/sysfs/mount.c @@ -28,7 +28,7 @@ static struct dentry *sysfs_mount(struct { struct dentry *root; void *ns; - bool new_sb; + bool new_sb = false; if (!(flags & MS_KERNMOUNT)) { if (!kobj_ns_current_may_mount(KOBJ_NS_TYPE_NET)) @@ -38,9 +38,9 @@ static struct dentry *sysfs_mount(struct 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; Patches currently in stable-queue which might be from viro@xxxxxxxxxxxxxxxxxx are queue-4.14/unfuck-sysfs_mount.patch queue-4.14/kernfs-deal-with-kernfs_fill_super-failures.patch