linux_dsm_epyc7002/arch/x86
Dave Hansen 6ba48ff46f x86: Remove arbitrary instruction size limit in instruction decoder
The current x86 instruction decoder steps along through the
instruction stream but always ensures that it never steps farther
than the largest possible instruction size (MAX_INSN_SIZE).

The MPX code is now going to be doing some decoding of userspace
instructions.  We copy those from userspace in to the kernel and
they're obviously completely untrusted coming from userspace.  In
addition to the constraint that instructions can only be so long,
we also have to be aware of how long the buffer is that came in
from userspace.  This _looks_ to be similar to what the perf and
kprobes is doing, but it's unclear to me whether they are
affected.

The whole reason we need this is that it is perfectly valid to be
executing an instruction within MAX_INSN_SIZE bytes of an
unreadable page. We should be able to gracefully handle short
reads in those cases.

This adds support to the decoder to record how long the buffer
being decoded is and to refuse to "validate" the instruction if
we would have gone over the end of the buffer to decode it.

The kprobes code probably needs to be looked at here a bit more
carefully.  This patch still respects the MAX_INSN_SIZE limit
there but the kprobes code does look like it might be able to
be a bit more strict than it currently is.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Jim Keniston <jkenisto@us.ibm.com>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: x86@kernel.org
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Link: http://lkml.kernel.org/r/20141114153957.E6B01535@viggo.jf.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-11-18 00:58:52 +01:00
..
boot Merge branch 'x86-efi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-10-23 14:45:09 -07:00
configs x86: Add "make tinyconfig" to configure the tiniest possible kernel 2014-08-08 16:30:24 -07:00
crypto Revert "crypto: aesni - disable "by8" AVX CTR optimization" 2014-10-02 14:40:28 +08:00
ia32 x86_64, entry: Fix out of bounds read on sysenter 2014-10-31 18:47:09 -07:00
include x86: Remove arbitrary instruction size limit in instruction decoder 2014-11-18 00:58:52 +01:00
kernel x86: Remove arbitrary instruction size limit in instruction decoder 2014-11-18 00:58:52 +01:00
kvm KVM: vmx: defer load of APIC access page address during reset 2014-11-02 08:37:18 +01:00
lguest
lib x86: Remove arbitrary instruction size limit in instruction decoder 2014-11-18 00:58:52 +01:00
math-emu
mm x86, pageattr: Prevent overflow in slow_virt_to_phys() for X86_PAE 2014-10-29 10:57:21 +01:00
net x86: bpf_jit: fix two bugs in eBPF JIT compiler 2014-10-14 13:13:14 -04:00
oprofile percpu: Resolve ambiguities in __get_cpu_var/cpumask_var_t 2014-08-28 08:58:57 -04:00
pci xen: features and fixes for 3.18-rc0 2014-10-11 20:29:01 -04:00
platform Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-10-31 14:30:16 -07:00
power nosave: consolidate __nosave_{begin,end} in <asm/sections.h> 2014-10-09 22:26:04 -04:00
purgatory arch/x86/purgatory/Makefile: try to use automatic variable in kexec purgatory makefile 2014-10-14 02:18:21 +02:00
realmode
syscalls bpf: enable bpf syscall on x64 and i386 2014-09-26 15:05:14 -04:00
tools x86: Remove arbitrary instruction size limit in instruction decoder 2014-11-18 00:58:52 +01:00
um Merge git://git.infradead.org/users/eparis/audit 2014-10-19 16:25:56 -07:00
vdso x86/vdso: Fix vdso2c's special_pages[] error checking 2014-09-24 09:55:38 +02:00
video
xen x86/xen: panic on bad Xen-provided memory map 2014-10-23 16:24:02 +01:00
.gitignore x86/build: Add arch/x86/purgatory/ make generated files to gitignore 2014-10-09 09:29:46 +02:00
Kbuild kexec: create a new config option CONFIG_KEXEC_FILE for new syscall 2014-08-29 16:28:16 -07:00
Kconfig perf/x86: Fix compile warnings for intel_uncore 2014-10-28 10:51:03 +01:00
Kconfig.cpu
Kconfig.debug
Makefile Merge branch 'x86-build-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-10-13 18:17:33 +02:00
Makefile_32.cpu
Makefile.um