[Lguest] [PATCH] Fix out-by-one error in traps.c

[Rusty Russell]

We don't care if ebp is on the stack, we care about ebp + 4.  Without
this, lguest (with CONFIG_DEBUG_LOCKDEP) can touch a page unmapped by
CONFIG_DEBUG_PAGEALLOC.

Signed-off-by: Rusty Russell <rusty at rustcorp.com.au>

diff -r b0b1ab8ecf48 arch/i386/kernel/traps.c
--- a/arch/i386/kernel/traps.c	Fri Aug 31 03:25:06 2007 +1000
+++ b/arch/i386/kernel/traps.c	Fri Aug 31 07:57:35 2007 +1000
@@ -100,7 +100,7 @@ print_context_stack(struct thread_info *tinfo,
 	unsigned long addr;
 
 #ifdef	CONFIG_FRAME_POINTER
-	while (valid_stack_ptr(tinfo, (void *)ebp)) {
+	while (valid_stack_ptr(tinfo, (void *)ebp + 4)) {
 		unsigned long new_ebp;
 		addr = *(unsigned long *)(ebp + 4);
 		ops->address(data, addr);