linux-kernel - Re: [patch 1/5] lib/vdso/32: Remove inconsistent NULL pointer checks

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Date:   Mon, 29 Jul 2019 07:52:34 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
        Andy Lutomirski <luto@...nel.org>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Kees Cook <keescook@...omium.org>,
        Paul Bolle <pebolle@...cali.nl>, Will Deacon <will@...nel.org>
Subject: Re: [patch 1/5] lib/vdso/32: Remove inconsistent NULL pointer checks

On Sun, Jul 28, 2019 at 03:12:52PM +0200, Thomas Gleixner 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

s/superflouos/superfluous

> will return -EFAULT anyway. That also gets rid of the dubious typecast
> which only works because the pointer is NULL.
> 
> Fixes: 00b26474c2f1 ("lib/vdso: Provide generic VDSO implementation")
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> ---