[PATCH 1/1] futex: remove duplicated code and fix UB

[Jiri Slaby]

On 06/23/2017, 09:51 AM, Thomas Gleixner wrote:
> On Wed, 21 Jun 2017, Jiri Slaby wrote:
>> diff --git a/arch/arm64/include/asm/futex.h b/arch/arm64/include/asm/futex.h
>> index f32b42e8725d..5bb2fd4674e7 100644
>> --- a/arch/arm64/include/asm/futex.h
>> +++ b/arch/arm64/include/asm/futex.h
>> @@ -48,20 +48,10 @@ do {									\
>>  } while (0)
>>  
>>  static inline int
>> -futex_atomic_op_inuser(unsigned int encoded_op, u32 __user *uaddr)
> 
> That unsigned int seems to be a change from the arm64 tree in next. It's
> not upstream and it'll cause a (easy to resolve) conflict.

Ugh, I thought the arm64 is in upstream already. Note that this patch
just takes what is in this arm64 fix and makes it effective for all
architectures. So I will wait with v2 until it merges upstream.

So, Will, will you incorporate Thomas' comments into your arm64 fix?

...

> Yes, we probably can't change that anymore, but at least we should make it
> very explicit and add a comment to that effect.

Something like this or do you want a comment yet?
        unsigned int op =         (encoded_op & 0x70000000) >> 28;
        unsigned int cmp =        (encoded_op & 0x0f000000) >> 24;
        int oparg = sign_extend32((encoded_op & 0x00fff000) >> 12, 12);
        int cmparg = sign_extend32(encoded_op & 0x00000fff, 12);

thanks,
-- 
js
suse labs