Re: [PATCH v2 6/7] percpu: Add __alloc_size attributes for better bounds checking

[Andrew Morton]

On Wed, 18 Aug 2021 14:40:20 -0700 Kees Cook <keescook@xxxxxxxxxxxx> wrote:

> As already done in GrapheneOS, add the __alloc_size attribute for
> appropriate percpu allocator interfaces, to provide additional hinting
> for better bounds checking, assisting CONFIG_FORTIFY_SOURCE and other
> compiler optimizations.
> 

Caught one, I assume:

In file included from ./include/linux/string.h:262,
                 from ./include/linux/bitmap.h:11,
                 from ./include/linux/cpumask.h:12,
                 from ./arch/x86/include/asm/cpumask.h:5,
                 from ./arch/x86/include/asm/msr.h:11,
                 from ./arch/x86/include/asm/processor.h:22,
                 from ./arch/x86/include/asm/cpufeature.h:5,
                 from ./arch/x86/include/asm/thread_info.h:53,
                 from ./include/linux/thread_info.h:60,
                 from ./arch/x86/include/asm/preempt.h:7,
                 from ./include/linux/preempt.h:78,
                 from ./include/linux/spinlock.h:55,
                 from ./include/linux/mmzone.h:8,
                 from ./include/linux/gfp.h:6,
                 from ./include/linux/slab.h:15,
                 from drivers/misc/lkdtm/heap.c:7:
In function 'memset',
    inlined from 'lkdtm_VMALLOC_LINEAR_OVERFLOW' at drivers/misc/lkdtm/heap.c:27:2:
./include/linux/fortify-string.h:172:3: error: call to '__write_overflow' declared with attribute error: detected write beyond size of object passed as 1st parameter
  172 |   __write_overflow();
      |   ^~~~~~~~~~~~~~~~~~
make[3]: *** [drivers/misc/lkdtm/heap.o] Error 1
make[2]: *** [drivers/misc/lkdtm] Error 2
make[1]: *** [drivers/misc] Error 2
make: *** [drivers] Error 2

I want to get a kernel release out, so I'll hide
mm-vmalloc-add-__alloc_size-attributes-for-better-bounds-checking.patch
for now.