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Subject[PATCH v4 0/3] x86: modify_ldt improvement, test, and config option
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Here's v3.  It fixes the "dazed and confused" issue, I hope.  It's also
probably a good general attack surface reduction, and it replaces some
scary code with IMO less scary code.

Also, servers and embedded systems should probably turn off modify_ldt.
This makes that possible.

Xen people, can you take a look at this?

Willy and Kees: I left the config option alone. The -tiny people will
like it, and we can always add a sysctl of some sort later.

Changes from v3:
- Hopefully fixed Xen.
- Fixed 32-bit test case on 32-bit native kernel.
- Fix bogus vumnap for some LDT sizes.
- Strengthen test case to check all LDT sizes (catches bogus vunmap).
- Lots of cleanups, mostly from Borislav.
- Simplify IPI code using on_each_cpu_mask.

Changes from v2:
- Allocate ldt_struct and the LDT entries separately. This should fix Xen.
- Stop using write_ldt_entry, since I'm pretty sure it's unnecessary now
that we no longer mutate an in-use LDT. (Xen people, can you check?)

Changes from v1:
- The config option is new.
- The test case is new.
- Fixed a missing allocation failure check.
- Fixed a use-after-free on fork().

Andy Lutomirski (3):
x86/ldt: Make modify_ldt synchronous
x86/ldt: Make modify_ldt optional
selftests/x86, x86/ldt: Add a selftest for modify_ldt

arch/x86/Kconfig | 17 ++
arch/x86/include/asm/desc.h | 15 --
arch/x86/include/asm/mmu.h | 5 +-
arch/x86/include/asm/mmu_context.h | 68 ++++-
arch/x86/kernel/Makefile | 3 +-
arch/x86/kernel/cpu/common.c | 4 +-
arch/x86/kernel/cpu/perf_event.c | 16 +-
arch/x86/kernel/ldt.c | 262 +++++++++---------
arch/x86/kernel/process_64.c | 6 +-
arch/x86/kernel/step.c | 8 +-
arch/x86/power/cpu.c | 3 +-
kernel/sys_ni.c | 1 +
tools/testing/selftests/x86/Makefile | 2 +-
tools/testing/selftests/x86/ldt_gdt.c | 492 ++++++++++++++++++++++++++++++++++
14 files changed, 747 insertions(+), 155 deletions(-)
create mode 100644 tools/testing/selftests/x86/ldt_gdt.c

--
2.4.3



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