From a1480dcc3c706e309a88884723446f2e84fedd5b Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Wed, 8 Oct 2014 12:32:47 -0700 Subject: [PATCH] fs: Add a missing permission check to do_umount Accessing do_remount_sb should require global CAP_SYS_ADMIN, but only one of the two call sites was appropriately protected. Fixes CVE-2014-7975. Signed-off-by: Andy Lutomirski --- fs/namespace.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/namespace.c b/fs/namespace.c index ef42d9bee212..7f67b463a5b4 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -1356,6 +1356,8 @@ static int do_umount(struct mount *mnt, int flags) * Special case for "unmounting" root ... * we just try to remount it readonly. */ + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; down_write(&sb->s_umount); if (!(sb->s_flags & MS_RDONLY)) retval = do_remount_sb(sb, MS_RDONLY, NULL, 0);