On 22.08.12 09:46:52, Willy Tarreau wrote:
> On Wed, Aug 22, 2012 at 10:21:07AM +0800, Junxiao Bi wrote:
> > If one kernel path is using KM_USER0 slot and is interrupted by
> > the oprofile nmi, then in copy_from_user_nmi(), the KM_USER0 slot
> > will be overwrite and cleared to zero at last, when the control
> > return to the original kernel path, it will access an invalid
> > virtual address and trigger a crash.
> > 
> > Cc: Robert Richter <[email protected]>
> > Cc: Greg KH <[email protected]>
> > Cc: [email protected]
> > Signed-off-by: Junxiao Bi <[email protected]>
> > 
> > Hi, Please review this patch.
> > 
> > It is for linux-2.6.32.y stable branch not for mainline.
> 
> BTW, is there a mainline equivalent commit ID ? A mainline ID is
> normally needed to merge anything into stable branches to ensure
> that no fix is lost when people upgrade. If this fix is part of
> another mainline commit, that's fine too.

This is a stable-only fix for kernels up to .36 as mainline changed in
between.

The code for copy_from_user_nmi() should be the same as in
arch/x86/kernel/cpu/perf_event.c.

-Robert

-- 
Advanced Micro Devices, Inc.
Operating System Research Center

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