[PATCH] x86_64: enlarge window for stack growth
authorChuck Ebbert <76306.1226@compuserve.com>
Mon, 26 Jun 2006 11:59:50 +0000 (13:59 +0200)
committerLinus Torvalds <torvalds@g5.osdl.org>
Mon, 26 Jun 2006 17:48:22 +0000 (10:48 -0700)
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 <76306.1226@compuserve.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
arch/x86_64/mm/fault.c

index 64728898f869369413e479cba984ace98953f5d0..4968a71df4aace77e6dbb56ac6305d895f082edb 100644 (file)
@@ -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))