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From: Thomas Gleixner <tglx@linutronix.de>
To: Andy Lutomirski <luto@kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>, X86 ML <x86@kernel.org>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	Kees Cook <keescook@chromium.org>,
	Paul Bolle <pebolle@tiscali.nl>, Will Deacon <will@kernel.org>
Subject: Re: [patch 1/5] lib/vdso/32: Remove inconsistent NULL pointer checks
Date: Sun, 28 Jul 2019 16:42:12 +0200 (CEST)	[thread overview]
Message-ID: <alpine.DEB.2.21.1907281640380.1791@nanos.tec.linutronix.de> (raw)
In-Reply-To: <CALCETrXbwPNt-SiudX+xup1vmkjksJpy-GJAT2K-g_dFw6d6vA@mail.gmail.com>

On Sun, 28 Jul 2019, Andy Lutomirski wrote:

> On Sun, Jul 28, 2019 at 6:20 AM Thomas Gleixner <tglx@linutronix.de> wrote:
> >
> > The 32bit variants of vdso_clock_gettime()/getres() have a NULL pointer
> > check for the timespec pointer. That's inconsistent vs. 64bit.
> >
> > But the vdso implementation will never be consistent versus the syscall
> > because the only case which it can handle is NULL. Any other invalid
> > pointer will cause a segfault. So special casing NULL is not really useful.
> >
> > Remove it along with the superflouos syscall fallback invocation as that
> > will return -EFAULT anyway. That also gets rid of the dubious typecast
> > which only works because the pointer is NULL.
> 
> Reviewed-by: Andy Lutomirski <luto@kernel.org>
> 
> FWIW, the equivalent change to gettimeofday would be an ABI break,
> since we historically have that check, and it even makes sense there.

Of course, because either of the two pointers can be NULL.

Thanks,

	tglx


  reply	other threads:[~2019-07-28 14:42 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-28 13:12 [patch 0/5] lib/vdso, x86/vdso: Fix fallout from generic VDSO conversion Thomas Gleixner
2019-07-28 13:12 ` [patch 1/5] lib/vdso/32: Remove inconsistent NULL pointer checks Thomas Gleixner
2019-07-28 14:33   ` Andy Lutomirski
2019-07-28 14:42     ` Thomas Gleixner [this message]
2019-07-28 15:30   ` Vincenzo Frascino
2019-07-29 14:52   ` Sean Christopherson
2019-07-30 22:19   ` [tip:timers/urgent] " tip-bot for Thomas Gleixner
2019-07-28 13:12 ` [patch 2/5] lib/vdso: Move fallback invocation to the callers Thomas Gleixner
2019-07-28 14:37   ` Andy Lutomirski
2019-07-28 15:31   ` Vincenzo Frascino
2019-07-30 22:19   ` [tip:timers/urgent] " tip-bot for Thomas Gleixner
2019-07-28 13:12 ` [patch 3/5] lib/vdso/32: Provide legacy syscall fallbacks Thomas Gleixner
2019-07-28 14:39   ` Andy Lutomirski
2019-07-28 15:33   ` Vincenzo Frascino
2019-07-29 14:48   ` Sean Christopherson
2019-07-30  9:38     ` [patch V2 " Thomas Gleixner
2019-07-30 14:28       ` Sean Christopherson
2019-07-30 20:09       ` Andy Lutomirski
2019-07-30 20:14         ` Thomas Gleixner
2019-07-30 22:20       ` [tip:timers/urgent] " tip-bot for Thomas Gleixner
2019-07-28 13:12 ` [patch 4/5] x86/vdso/32: Use 32bit syscall fallback Thomas Gleixner
2019-07-28 14:50   ` Andy Lutomirski
2019-07-29 11:23   ` Vincenzo Frascino
2019-07-29 14:51   ` Sean Christopherson
2019-07-30 22:21   ` [tip:timers/urgent] " tip-bot for Thomas Gleixner
2019-07-28 13:12 ` [patch 5/5] arm64: compat: vdso: Use legacy syscalls as fallback Thomas Gleixner
2019-07-28 15:35   ` Vincenzo Frascino
2019-07-30 22:22   ` [tip:timers/urgent] " tip-bot for Thomas Gleixner

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