Messages in this thread | | | Date | Fri, 31 Jul 2015 09:44:24 -0400 | From | Boris Ostrovsky <> | Subject | Re: [PATCH v6 0/4] x86: modify_ldt improvement, test, and config option |
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On 07/31/2015 05:10 AM, Andrew Cooper wrote: > On 30/07/15 22:31, Andy Lutomirski wrote: >> This is intended for x86/urgent. Sorry for taking so long, but it >> seemed nice to avoid breaking Xen. > Very much appreciated. Thanks! > >> This fixes the "dazed and confused" issue which was exposed by the >> CVE-2015-5157 fix. 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 test patch 1? It works for me on my evil 32-bit >> Xen virtio setup. > So the LDT issue seems to have gone away, which is good. > > However, I did get this from my single vcpu guest test > > [OK] LDT entry 0 is invalid > [SKIP] Cannot set affinity to CPU 1 > [RUN] Test exec > [ 3.638967] CPU 0 set the LDT > [OK] LDT entry 0 has AR 0x0040FA00 and limit 0x0000002A > [ 3.639380] ------------[ cut here ]------------ > [ 3.639389] WARNING: CPU: 0 PID: 383 at > /local/linux-mainline.git/arch/x86/include/asm/mmu_context.h:96 > flush_old_exec+0x7fd/0xb70() > [ 3.639397] DEBUG_LOCKS_WARN_ON(!irqs_disabled())
You must be running v5 (or earlier). This is fixed in v6 --- it is now 'DEBUG_LOCKS_WARN_ON(preemptible());'
-boris
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