linux-kernel - Re: [PATCH] x86, vsyscall: Fix build warning in vsyscall

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Date:	Sat, 11 Jun 2011 07:01:57 -0400
From:	Andrew Lutomirski <luto@....edu>
To:	Rakib Mullick <rakib.mullick@...il.com>
Cc:	mingo@...e.hu, hpa@...or.com, tglx@...utronix.de, x86@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86, vsyscall: Fix build warning in vsyscall_64.c

On Sat, Jun 11, 2011 at 3:31 AM, Rakib Mullick <rakib.mullick@...il.com> wrote:
> Due to commit 5cec93c216db77 (x86-64: Emulate legacy vsyscalls), we get the following warning:
>
>   arch/x86/kernel/vsyscall_64.c: In function ‘do_emulate_vsyscall’:
>   arch/x86/kernel/vsyscall_64.c:111:7: warning: ‘ret’ may be used uninitialized in this function

What's the code path that uses ret without initializing it?

> -       if (ret == -EFAULT) {
> +       if (ret == -EFAULT || ret == -EINVAL) {
>                /*
>                 * Bad news -- userspace fed a bad pointer to a vsyscall.
>                 *

EINVAL doesn't seem like grounds to fault.  (I'm not sure how to get
EINVAL from time, gettimeofday, or getcpu, but in case there is, we
should return it back to userspace.)

--Andy
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