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authorKees Cook <keescook@chromium.org>2013-04-10 12:24:22 -0700
committerH. Peter Anvin <hpa@linux.intel.com>2013-04-11 13:53:19 -0700
commit4eefbe792baedb474e256d35370849992fcf1c79 (patch)
tree03a95dab4a014a7f36133f9660ca180b01df62d4 /arch/x86/xen
parent31880c37c11e28cb81c70757e38392b42e695dc6 (diff)
x86: Use a read-only IDT alias on all CPUs
Make a copy of the IDT (as seen via the "sidt" instruction) read-only. This primarily removes the IDT from being a target for arbitrary memory write attacks, and has the added benefit of also not leaking the kernel base offset, if it has been relocated. We already did this on vendor == Intel and family == 5 because of the F0 0F bug -- regardless of if a particular CPU had the F0 0F bug or not. Since the workaround was so cheap, there simply was no reason to be very specific. This patch extends the readonly alias to all CPUs, but does not activate the #PF to #UD conversion code needed to deliver the proper exception in the F0 0F case except on Intel family 5 processors. Signed-off-by: Kees Cook <keescook@chromium.org> Link: http://lkml.kernel.org/r/20130410192422.GA17344@www.outflux.net Cc: Eric Northup <digitaleric@google.com> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Diffstat (limited to 'arch/x86/xen')
-rw-r--r--arch/x86/xen/mmu.c4
1 files changed, 1 insertions, 3 deletions
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 6afbb2ca9a0a..8bc4decb14ca 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -2039,9 +2039,7 @@ static void xen_set_fixmap(unsigned idx, phys_addr_t phys, pgprot_t prot)
switch (idx) {
case FIX_BTMAP_END ... FIX_BTMAP_BEGIN:
-#ifdef CONFIG_X86_F00F_BUG
- case FIX_F00F_IDT:
-#endif
+ case FIX_RO_IDT:
#ifdef CONFIG_X86_32
case FIX_WP_TEST:
case FIX_VDSO: