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SubjectRe: [PATCH] x86/nmi/64: avoid passing user space rsp of pt_regs to nmi handler
On Tue, Aug 22, 2017 at 05:09:19PM +0000, yang oliver wrote:
> From: Yong Yang <yangoliver@gmail.com>
>
> While NMI interrupts the very beginning of SYSCALL, the rsp could
> be still user space address without loading kernel address. Then
> the pt_regs constructed by the NMI entry point could have a user
> space rsp. If a NMI handler tried to dump stack by using this rsp,
> it can cause the kernel panic.

To me this sounds like an unwinder bug. The unwinder is supposed to
have checks to prevent it from accessing user space. I know you had
previously reported this for an older (pre-4.9) kernel. Have you
verified the bug still exists on a recent kernel?

--
Josh

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