Messages in this thread | | | Date | Mon, 26 Apr 2021 18:55:34 +0200 | From | Greg Kroah-Hartman <> | Subject | Re: [PATCH 113/190] Revert "x86/hpet: Prevent potential NULL pointer dereference" |
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On Fri, Apr 23, 2021 at 02:03:50AM -0700, Kees Cook wrote: > On Fri, Apr 23, 2021 at 01:33:07AM +0200, Thomas Gleixner wrote: > > On Wed, Apr 21 2021 at 12:49, Kees Cook wrote: > > > On Wed, Apr 21, 2021 at 02:59:48PM +0200, Greg Kroah-Hartman wrote: > > >> diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c > > >> index 08651a4e6aa0..0515a97bf6f5 100644 > > >> --- a/arch/x86/kernel/hpet.c > > >> +++ b/arch/x86/kernel/hpet.c > > >> @@ -930,8 +930,6 @@ int __init hpet_enable(void) > > >> return 0; > > >> > > >> hpet_set_mapping(); > > >> - if (!hpet_virt_address) > > >> - return 0; > > >> > > >> /* Validate that the config register is working */ > > >> if (!hpet_cfg_working()) > > > > > > FWIW, this patch looks harmless. It is checking for a failure in > > > hpet_set_mapping(), and avoids the following code from performing > > > 0-offset reads. hpet_set_mapping() is likely to never fail in real-world > > > situations. *shrug* > > > > 'likely never to fail' is clearly a receipe for disaster and you should > > know that. > > Of course -- I prefer to keep the sanity check. It just wasn't as good > as it could have been: it's not clear just by looking at the patch how > hpet_virt_address and hpet_set_mapping() are related. > > > > > > I think it would make more sense for the check to live in > > > hpet_cfg_working(), though. > > > > No. That does not make any sense at all. > > > > The proper change would have been to make hpet_set_mapping() return > > an error/success code and act on that. > > > > But that does _NOT_ make the patch invalid. > > > > I'm pretty sure that I looked at it and thought about the proper > > solution (see above) and then shrugged it off because of overload... > > Right, no, I was saying the original patch should stay. It shouldn't be > reverted. > > Greg, please drop this patch from the revert list.
Now dropped, thanks for the review.
greg k-h
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