[PATCH] x86_64: enlarge window for stack growth

Allow stack growth so the 'enter' instruction works. Also fixes problem in compat_sys_kexec_load() which could allocate more than 128 bytes using compat_alloc_user_space(). Signed-off-by: Chuck Ebbert <[email protected]> Signed-off-by: Andi Kleen <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
mna · Jun 26, 2006 · 03fdc2c · 03fdc2c
1 parent 6bfa9bb
commit 03fdc2c
Showing 1 changed file with 4 additions and 2 deletions.
diff --git a/arch/x86_64/mm/fault.c b/arch/x86_64/mm/fault.c
@@ -410,8 +410,10 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
 	if (!(vma->vm_flags & VM_GROWSDOWN))
 		goto bad_area;
 	if (error_code & 4) {
-		// XXX: align red zone size with ABI 
-		if (address + 128 < regs->rsp)
+		/* Allow userspace just enough access below the stack pointer
+		 * to let the 'enter' instruction work.
+		 */
+		if (address + 65536 + 32 * sizeof(unsigned long) < regs->rsp)
 			goto bad_area;
 	}
 	if (expand_stack(vma, address))