[PATCH] error out on execve with no binfmts

Early calls to userspace can invoke an execve() before any binfmt handlers
are registered.  Properly return an error in this case rather than 0.
On at least one arch (x86_64) without this patch, the system will double
fault on early attempts to call_usermodehelper.
Signed-off-by: Chris Wright <chrisw@osdl.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

fs/exec.c

@@ -984,7 +984,7 @@ EXPORT_SYMBOL(remove_arg_zero);
  */
 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
 {
-	int try,retval=0;
+	int try,retval;
 	struct linux_binfmt *fmt;
 #ifdef __alpha__
 	/* handle /sbin/loader.. */
@@ -1028,6 +1028,7 @@ int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
 	/* kernel module loader fixup */
 	/* so we don't try to load run modprobe in kernel space. */
 	set_fs(USER_DS);
+	retval = -ENOENT;
 	for (try=0; try<2; try++) {
 		read_lock(&binfmt_lock);
 		for (fmt = formats ; fmt ; fmt = fmt->next) {