x86, vdso: Fix an OOPS accessing the HPET mapping w/o an HPET
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 <35951e2654371df7c68de546b20b3c3794b62aae@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.

Cc: Stefani Seibold <35951e2654371df7c68de546b20b3c3794b62aae@seibold.net>
Reported-by: Sasha Levin <e642b69ed2fc111e09ffdc37feb733a52253340d@oracle.com>
Signed-off-by: Andy Lutomirski <2cc0d0d76de2e6f37b92deeb83c85cb306fc5dc1@amacapital.net>
Link: http://lkml.kernel.org/r/c8b0a9a0b8d011a8b273cbb2de88d37190ed2751.1400538962.git.2cc0d0d76de2e6f37b92deeb83c85cb306fc5dc1@amacapital.net
Signed-off-by: H. Peter Anvin <8a453bad9912ffe59bc0f0b8abe03df9be19379e@linux.intel.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs