linux/arch/i386
Andi Kleen 18bd057b14 [PATCH] i386/x86-64: Fix x87 information leak between processes
AMD K7/K8 CPUs only save/restore the FOP/FIP/FDP x87 registers in FXSAVE
when an exception is pending.  This means the value leak through
context switches and allow processes to observe some x87 instruction
state of other processes.

This was actually documented by AMD, but nobody recognized it as
being different from Intel before.

The fix first adds an optimization: instead of unconditionally
calling FNCLEX after each FXSAVE test if ES is pending and skip
it when not needed. Then do a x87 load from a kernel variable to
clear FOP/FIP/FDP.

This means other processes always will only see a constant value
defined by the kernel in their FP state.

I took some pain to make sure to chose a variable that's already
in L1 during context switch to make the overhead of this low.

Also alternative() is used to patch away the new code on CPUs
who don't need it.

Patch for both i386/x86-64.

The problem was discovered originally by Jan Beulich. Richard
Brunner provided the basic code for the workarounds, with contribution
from Jan.

This is CVE-2006-1056

Cc: richard.brunner@amd.com
Cc: jbeulich@novell.com

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-04-20 07:58:11 -07:00
..
boot [PATCH] vesafb: Fix incorrect logo colors in x86_64 2006-04-11 06:18:54 -07:00
crypto [CRYPTO] aes-i586: Remove unused variable ls_tab 2006-01-09 14:15:53 -08:00
kernel [PATCH] i386/x86-64: Fix x87 information leak between processes 2006-04-20 07:58:11 -07:00
lib [LIB]: Consolidate _atomic_dec_and_lock() 2005-09-14 21:47:01 -07:00
mach-default [PATCH] Fix topology.c location 2006-02-24 14:31:39 -08:00
mach-es7000 [PATCH] Compilation fix for ES7000 when no ACPI is specified in config (i386) 2006-03-23 07:38:04 -08:00
mach-generic [PATCH] x86: sutomatically enable bigsmp when we have more than 8 CPUs 2005-09-05 00:06:10 -07:00
mach-visws [PATCH] kill include/linux/platform.h, default_idle() cleanup 2006-03-24 07:33:21 -08:00
mach-voyager [PATCH] voyager: no need to define BITS_PER_BYTE when it's already in types.h 2006-04-19 09:13:51 -07:00
math-emu [PATCH] i386: inline assembler: cleanup and encapsulate descriptor and task register management 2005-09-05 00:06:11 -07:00
mm [PATCH] x86_64: Support memory hotadd without sparsemem 2006-04-09 11:53:16 -07:00
oprofile [PATCH] for_each_possible_cpu: i386 2006-03-28 09:16:05 -08:00
pci [PATCH] arch/i386/pci/irq.c - new VIA chipsets (fwd) 2006-04-14 12:25:25 -07:00
power [PATCH] x86: add MCE resume 2005-11-07 07:53:30 -08:00
Kconfig [PATCH] Configurable NODES_SHIFT 2006-04-11 06:18:39 -07:00
Kconfig.cpu [PATCH] Enable TSC for AMD Geode GX/LX 2006-04-11 06:18:34 -07:00
Kconfig.debug [PATCH] i386: Move CONFIG_DOUBLEFAULT into arch/i386 where it belongs. 2006-04-18 10:39:20 -07:00
Makefile [PATCH] x86: "make isoimage" support; FDINITRD= support; minor cleanups 2006-03-26 08:56:53 -08:00
Makefile.cpu [PATCH] x86-64: Use -mtune=generic for generic kernels 2006-03-25 09:10:52 -08:00
defconfig update the i386 defconfig 2006-03-20 20:14:06 +01:00