x86,vdso: fix an OOPS accessing the hpet mapping w/o an hpet

The oops can be triggered in qemu using -no-hpet (but not nohpet) by
reading a couple of pages past the end of the vdso text.  This should send
SIGBUS instead of OOPSing.

The bug was introduced by:

commit 7a59ed415f5b57469e22e41fc4188d5399e0b194
Author: Stefani Seibold <stefani@seibold.net>
Date:   Mon Mar 17 23:22:09 2014 +0100

    x86, vdso: Add 32 bit VDSO time support for 32 bit kernel

which is new in 3.15.

This will be fixed separately in 3.15, but that patch will not apply to
tip/x86/vdso.  This is the equivalent fix for tip/x86/vdso and,
presumably, 3.16.

Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Stefani Seibold <stefani@seibold.net>
Cc: <stable@vger.kernel.org>	[needs rework for 3.15 and earlier]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/arch/x86/vdso/vma.c b/arch/x86/vdso/vma.c
index e915eaec4f961bc83b69aa525e5c465324b6a133..8ad0081df7a83c489db4be0e528d440e55fae544 100644 (file)
--- a/arch/x86/vdso/vma.c
+++ b/arch/x86/vdso/vma.c
@@ -90,6 +90,7 @@ static int map_vdso(const struct vdso_image *image, bool calculate_addr)
        struct vm_area_struct *vma;
        unsigned long addr;
        int ret = 0;
+       static struct page *no_pages[] = {NULL};
 
        if (calculate_addr) {
                addr = vdso_addr(current->mm->start_stack,
@@ -125,7 +126,7 @@ static int map_vdso(const struct vdso_image *image, bool calculate_addr)
                                       addr + image->size,
                                       image->sym_end_mapping - image->size,
                                       VM_READ,
-                                      NULL);
+                                      no_pages);
 
        if (IS_ERR(vma)) {
                ret = PTR_ERR(vma);