On Thu, Sep 28, 2023 at 02:53:09PM +1000, Greg Ungerer wrote:
> Hi Kees,
>
> On 28/9/23 01:59, Kees Cook wrote:
> > On Wed, Sep 27, 2023 at 11:29:33PM +1000, Greg Ungerer wrote:
> > > The binfmt_elf_fdpic loader has some debug trace that can be enabled at
> > > build time. The recent 64-bit additions cause some warnings if that
> > > debug is enabled, such as:
> > >
> > > fs/binfmt_elf_fdpic.c: In function ‘elf_fdpic_map_file’:
> > > fs/binfmt_elf_fdpic.c:46:33: warning: format ‘%x’ expects argument of type ‘unsigned int’, but argument 3 has type ‘Elf64_Addr’ {aka ‘long long unsigned int’} [-Wformat=]
> > > 46 | #define kdebug(fmt, ...) printk("FDPIC "fmt"\n" ,##__VA_ARGS__ )
> > > | ^~~~~~~~
> > > ./include/linux/printk.h:427:25: note: in definition of macro ‘printk_index_wrap’
> > > 427 | _p_func(_fmt, ##__VA_ARGS__); \
> > > | ^~~~
> > >
> > > Cast values to the largest possible type (which is equivilent to unsigned
> > > long long in this case) and use appropriate format specifiers to match.
> >
> > It seems like these should all just be "unsigned long", yes?
>
> Some of them yes, but not all.
> For example trying to use unsigned long in the last chunk of this patch:
>
> fs/binfmt_elf_fdpic.c: In function ‘elf_fdpic_map_file_by_direct_mmap’:
> fs/binfmt_elf_fdpic.c:46:33: warning: format ‘%lx’ expects argument of type ‘long unsigned int’, but argument 3 has type ‘long long unsigned int’ [-Wformat=]
Oh, something is actually using "long long" already. :P Gotcha. Thanks!
-Kees
--
Kees Cook
