From: Avi Kivity <avi@redhat.com>
To: Andi Kleen <andi@firstfloor.org>
Cc: x86@kernel.org, Ingo Molnar <mingo@elte.hu>,
linux-kernel <linux-kernel@vger.kernel.org>,
KVM list <kvm@vger.kernel.org>
Subject: Re: [PATCH 0/3] Remove interrupt stack table usage from x86_64 kernel
Date: Sun, 28 Dec 2008 16:09:26 +0200 [thread overview]
Message-ID: <49578896.8030703@redhat.com> (raw)
In-Reply-To: <20081228131605.GC496@one.firstfloor.org>
(restoring cc list)
Andi Kleen wrote:
> One of the other problems: NMIs and MCEs have the same problem with SYSCALL
>
This one however looks unsolvable. Userspace can point %rsp into
arbitrary memory, issue a syscall, and hope for an nmi. Since we're in
cpl 0 and are not using IST, the processor will not switch stacks, and
the nmi stack frame will corrupt any memory the user chooses to point to.
Even without a malicious user, %rsp could legitimately point at unmapped
memory.
I don't see how syscall could work on i386, and indeed:
> vdso32.so-$(VDSO32-y) += int80
> vdso32.so-$(CONFIG_COMPAT) += syscall
> vdso32.so-$(VDSO32-y) += sysenter
It's disabled. Is that the reason?
--
error compiling committee.c: too many arguments to function
next prev parent reply other threads:[~2008-12-28 14:10 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-12-25 20:58 [PATCH 0/3] Remove interrupt stack table usage from x86_64 kernel Avi Kivity
2008-12-25 20:58 ` [PATCH 1/3] x86: drop the use of the tss interrupt stack table (IST) Avi Kivity
2008-12-25 20:58 ` [PATCH 2/3] x86: Remove pda.irqcount Avi Kivity
2008-12-25 20:58 ` [PATCH 3/3] x86: Switch critical exceptions and NMI to irqstack Avi Kivity
2008-12-26 9:15 ` [PATCH 0/3] Remove interrupt stack table usage from x86_64 kernel Ingo Molnar
[not found] ` <87vdt5vfxc.fsf@basil.nowhere.org>
[not found] ` <4956A0B1.1060908@redhat.com>
[not found] ` <20081227224029.GB496@one.firstfloor.org>
[not found] ` <49573FE7.9090802@redhat.com>
[not found] ` <20081228131605.GC496@one.firstfloor.org>
2008-12-28 14:09 ` Avi Kivity [this message]
2008-12-28 19:08 ` Andi Kleen
2008-12-28 19:07 ` Avi Kivity
2008-12-28 19:19 ` Avi Kivity
2008-12-28 20:08 ` Avi Kivity
2008-12-28 20:34 ` Andi Kleen
2008-12-28 20:28 ` Avi Kivity
2008-12-28 19:30 ` Andi Kleen
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