Subject: Re: [PATCH 3/4] x86: Implement strict user copy checks for x86_64

From: Andrew Morton <[email-masked]>
Date: Thu, 7 Jul 2011 14:54:13 -0700

On Tue, 31 May 2011 11:14:32 -0700
Stephen Boyd <[email-masked]> wrote:

> Strict user copy checks are only really supported on x86_32 even
> though the config option is selectable on x86_64. Add the
> necessary support to the 64 bit code to trigger copy_from_user()
> warnings at compile time.

I'm still reluctant to go and throw a pile of warnings into many
people's faces without having made an attempt to fix them.

We get a screen full of these:

    inlined from 'pktgen_if_write' at net/core/pktgen.c:877:
/usr/src/devel/arch/x86/include/asm/uaccess_64.h:64: warning: call to 'copy_from_user_overflow' declared with attribute warning: copy_from_user() buffer size is not provably correct
In function 'copy_from_user',
    inlined from 'pktgen_if_write' at net/core/pktgen.c:1145:
/usr/src/devel/arch/x86/include/asm/uaccess_64.h:64: warning: call to 'copy_from_user_overflow' declared with attribute warning: copy_from_user() buffer size is not provably correct
In function 'copy_from_user',
...

and I don't immediately see a way of suppressing them without adding
additional code.

Ideas?