From 71a3424628dd7d8813e0d077dc023c957481f29f Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Thu, 14 Nov 2013 21:22:25 -0800 Subject: [PATCH] vfs: Fix a regression in mounting proc commit 41301ae78a99ead04ea42672a1ab72c6f44cc81d upstream. Gao feng reported that commit e51db73532955dc5eaba4235e62b74b460709d5b userns: Better restrictions on when proc and sysfs can be mounted caused a regression on mounting a new instance of proc in a mount namespace created with user namespace privileges, when binfmt_misc is mounted on /proc/sys/fs/binfmt_misc. This is an unintended regression caused by the absolutely bogus empty directory check in fs_fully_visible. The check fs_fully_visible replaced didn't even bother to attempt to verify proc was fully visible and hiding proc files with any kind of mount is rare. So for now fix the userspace regression by allowing directory with nlink == 1 as /proc/sys/fs/binfmt_misc has. I will have a better patch but it is not stable material, or last minute kernel material. So it will have to wait. Acked-by: Serge Hallyn Acked-by: Gao feng Tested-by: Gao feng Signed-off-by: "Eric W. Biederman" Signed-off-by: Greg Kroah-Hartman --- fs/namespace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/namespace.c b/fs/namespace.c index da5c494..84447db 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -2888,7 +2888,7 @@ bool fs_fully_visible(struct file_system_type *type) struct inode *inode = child->mnt_mountpoint->d_inode; if (!S_ISDIR(inode->i_mode)) goto next; - if (inode->i_nlink != 2) + if (inode->i_nlink > 2) goto next; } visible = true; -- 2.7.4