1 files changed, 16 insertions, 4 deletions

diff --git a/fs/open.c b/fs/open.c
index 54198538b67e..3fa4e4ffce4c 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -335,7 +335,7 @@ asmlinkage long sys_ftruncate(unsigned int fd, unsigned long length)
 {
         long ret = do_sys_ftruncate(fd, length, 1);
         /* avoid REGPARM breakage on x86: */
-        prevent_tail_call(ret);
+        asmlinkage_protect(2, ret, fd, length);
         return ret;
 }
 
@@ -350,7 +350,7 @@ asmlinkage long sys_ftruncate64(unsigned int fd, loff_t length)
 {
         long ret = do_sys_ftruncate(fd, length, 0);
         /* avoid REGPARM breakage on x86: */
-        prevent_tail_call(ret);
+        asmlinkage_protect(2, ret, fd, length);
         return ret;
 }
 #endif
@@ -903,6 +903,18 @@ struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags)
         int error;
         struct file *f;
 
+        /*
+         * We must always pass in a valid mount pointer.   Historically
+         * callers got away with not passing it, but we must enforce this at
+         * the earliest possible point now to avoid strange problems deep in the
+         * filesystem stack.
+         */
+        if (!mnt) {
+                printk(KERN_WARNING "%s called with NULL vfsmount\n", __func__);
+                dump_stack();
+                return ERR_PTR(-EINVAL);
+        }
+
         error = -ENFILE;
         f = get_empty_filp();
         if (f == NULL) {
@@ -1055,7 +1067,7 @@ asmlinkage long sys_open(const char __user *filename, int flags, int mode)
 
         ret = do_sys_open(AT_FDCWD, filename, flags, mode);
         /* avoid REGPARM breakage on x86: */
-        prevent_tail_call(ret);
+        asmlinkage_protect(3, ret, filename, flags, mode);
         return ret;
 }
 
@@ -1069,7 +1081,7 @@ asmlinkage long sys_openat(int dfd, const char __user *filename, int flags,
 
         ret = do_sys_open(dfd, filename, flags, mode);
         /* avoid REGPARM breakage on x86: */
-        prevent_tail_call(ret);
+        asmlinkage_protect(4, ret, dfd, filename, flags, mode);
         return ret;
 }