linux-kernel - RE: [PATCH v2 05/18] x86: remove __range_not

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Date:   Fri, 18 Feb 2022 15:45:56 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Christoph Hellwig' <hch@....de>, Arnd Bergmann <arnd@...nel.org>
CC:     Linus Torvalds <torvalds@...ux-foundation.org>,
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        Christoph Hellwig <hch@...radead.org>
Subject: RE: [PATCH v2 05/18] x86: remove __range_not_ok()

From: Christoph Hellwig
> Sent: 18 February 2022 06:29
...
> 
> > diff --git a/arch/x86/kernel/stacktrace.c b/arch/x86/kernel/stacktrace.c
> > index 15b058eefc4e..ee117fcf46ed 100644
> > --- a/arch/x86/kernel/stacktrace.c
> > +++ b/arch/x86/kernel/stacktrace.c
> > @@ -90,7 +90,7 @@ copy_stack_frame(const struct stack_frame_user __user *fp,
> >  {
> >  	int ret;
> >
> > -	if (__range_not_ok(fp, sizeof(*frame), TASK_SIZE))
> > +	if (!__access_ok(fp, sizeof(*frame)))
> >  		return 0;
> 
> Just switch the __get_user calls below to get_user instead.

Is this worth doing at all?
How much userspace code is actually compiled with stack frames?

Won't work well for a 32bit process on a 64bit kernel either.

	David

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