Re: [kbuild-all] Re: [tip:x86/cpu 2/3] arch/x86/kernel/alternative.c:96:10: warning: Undefined behaviour, pointer arithmetic 'x86nops+10' is out of bounds.

[Rong Chen]

On 3/16/21 4:27 PM, Borislav Petkov wrote:
> Yet another useless report!
>
> On Tue, Mar 16, 2021 at 07:50:10AM +0800, kernel test robot wrote:
> > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86/cpu
> > head:   301cddc21a157a3072d789a3097857202e550a24
> > commit: a89dfde3dc3c2dbf56910af75e2d8b11ec5308f6 [2/3] x86: Remove dynamic NOP selection
> > compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
> >
> > If you fix the issue, kindly add following tag as appropriate
> > Reported-by: kernel test robot <lkp@xxxxxxxxx>
> >
> >
> > cppcheck possible warnings: (new ones prefixed by >>, may not real problems)
> What's cppcheck?
>
> That?
>
> Description-en: tool for static C/C++ code analysis (CLI)
>   Cppcheck is a command-line tool that tries to detect bugs that your
>
>
> > > > arch/x86/kernel/alternative.c:96:10: warning: Undefined behaviour, pointer arithmetic 'x86nops+10' is out of bounds. [pointerOutOfBounds]
> >      x86nops + 1 + 2 + 3 + 4,
> >              ^
> >     arch/x86/kernel/alternative.c:97:10: warning: Undefined behaviour, pointer arithmetic 'x86nops+15' is out of bounds. [pointerOutOfBounds]
> >      x86nops + 1 + 2 + 3 + 4 + 5,
> >              ^
> >     arch/x86/kernel/alternative.c:98:10: warning: Undefined behaviour, pointer arithmetic 'x86nops+21' is out of bounds. [pointerOutOfBounds]
> >      x86nops + 1 + 2 + 3 + 4 + 5 + 6,
> >              ^
> >     arch/x86/kernel/alternative.c:99:10: warning: Undefined behaviour, pointer arithmetic 'x86nops+28' is out of bounds. [pointerOutOfBounds]
> >      x86nops + 1 + 2 + 3 + 4 + 5 + 6 + 7,
> >              ^
> > > > arch/x86/kernel/ftrace.c:304:7: warning: union member 'ftrace_op_code_union::code' is never used. [unusedStructMember]
> >      char code[OP_REF_SIZE];
> >           ^
> How do you trigger this?
>
> /me ignores it until there's some info on how those things can be
> reproduced.

Hi Borislav,

Sorry for the inconvenience, there's a bug in our system which sent 
internal reports to outside.
please ignore the warnings.

Best Regards,
Rong Chen