4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> [ Upstream commit 75422726b0f717d67db3283c2eb5bc14fa2619c5 ] Add MS_KERNMOUNT to the flags that are passed. Use sget_userns and force &init_user_ns instead of calling sget so that even if called from a weird context the internal filesystem will be considered to be in the intial user namespace. Luis Ressel reported that the the failure to pass MS_KERNMOUNT into mount_pseudo broke his in development graphics driver that uses the generic drm infrastructure. I am not certain the deriver was bug free in it's usage of that infrastructure but since mount_pseudo_xattr can never be triggered by userspace it is clearer and less error prone, and less problematic for the code to be explicit. Reported-by: Luis Ressel <aranea@xxxxxxxx> Tested-by: Luis Ressel <aranea@xxxxxxxx> Acked-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/libfs.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/fs/libfs.c +++ b/fs/libfs.c @@ -245,7 +245,8 @@ struct dentry *mount_pseudo_xattr(struct struct inode *root; struct qstr d_name = QSTR_INIT(name, strlen(name)); - s = sget(fs_type, NULL, set_anon_super, MS_NOUSER, NULL); + s = sget_userns(fs_type, NULL, set_anon_super, MS_KERNMOUNT|MS_NOUSER, + &init_user_ns, NULL); if (IS_ERR(s)) return ERR_CAST(s);