linux-kernel - Re: [PATCH 2/2] x86: fix _

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Message-ID: <e2dcebe0a663bdf5496e444509f3e45f@codethink.co.uk>
Date:   Fri, 29 Mar 2019 15:24:48 +0000
From:   Ben Dooks <ben.dooks@...ethink.co.uk>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Jann Horn <jannh@...gle.com>, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Qiaowei Ren <qiaowei.ren@...el.com>
Subject: Re: [PATCH 2/2] x86: fix __user annotations



On 2019-03-29 13:39, Borislav Petkov wrote:
> On Thu, Mar 28, 2019 at 10:23:21PM +0100, Jann Horn wrote:
>> Fix __user annotations in various places across the x86 tree:
>> 
>>  - cast to wrong pointer type in __user_atomic_cmpxchg_inatomic()
>>  - generic_load_microcode() deals with a pointer that can be either a
>>    kernel pointer or a user pointer; change the code to pass it around 
>> as
>>    a __user pointer, and add explicit casts to convert between __user 
>> and
>>    __kernel
>>  - save_xstate_epilog() has missing __user in explicit casts
>>  - setup_sigcontext() and x32_setup_rt_frame() rely on the cast 
>> performed
>>    by put_user_ex() on its first argument, but sparse requires __force 
>> for
>>    casting __user pointers to unsigned long
>>  - xen_hvm_config() has missing __user
>> 
>> This patch removes all sparse warnings about the asn:1 address space
>> (__user) in arch/x86/ for my kernel config.
>> 
>> Signed-off-by: Jann Horn <jannh@...gle.com>
>> ---
>> This patch requires the previous one, "[PATCH 1/2] kernel.h: use
>> parentheses around argument in u64_to_user_ptr()", otherwise
>> xen_hvm_config() breaks. Can we take both together through the x86 
>> tree,
>> or does the first one have to go through akpm's tree?
> 
> I don't see why not, unless akpm has objections.
> 
> However,
> 
>>  arch/x86/include/asm/uaccess.h        |  3 +--
>>  arch/x86/include/asm/uaccess_64.h     |  2 +-
> 
> This chunk is being discussed here already:
> 
> https://lkml.kernel.org/r/20190228185027.2480-1-ben.dooks@codethink.co.uk
> 
> and I'd like to take Ben's v2 when Ben adds Linus' explanation.

I'll sort that out in a bit, thanks for reviewing.