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

Borislav Petkov
2019-03-29T13:39:58Z

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.

Then, it would be probably easier if you could split that patch into:

> arch/x86/kernel/cpu/microcode/intel.c | 20 ++++++++++++--------

microcode

> arch/x86/kernel/fpu/signal.c | 6 +++---
> arch/x86/kernel/signal.c | 4 ++--

fpu patch

> arch/x86/kvm/x86.c | 8 ++++----

kvm patch

which would make review/merging/etc considerably easier.

Thx.

--
Regards/Gruss,
Boris.

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