Re: [PATCH 2/2] x86: fix __user annotations

Ben Dooks
2019-03-29T15:25:07Z

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@google.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.