From: Kees Cook <keescook@chromium.org>
To: Greg Ungerer <gerg@kernel.org>
Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, palmer@rivosinc.com,
ebiederm@xmission.com, brauner@kernel.org,
viro@zeniv.linux.org.uk
Subject: Re: [PATCH] binfmt_elf_fdpic: clean up debug warnings
Date: Fri, 29 Sep 2023 10:58:09 -0700 [thread overview]
Message-ID: <202309291057.6D4993BA@keescook> (raw)
In-Reply-To: <9e4cf2c9-a1a9-43a8-3f72-2824301bbc98@kernel.org>
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
next prev parent reply other threads:[~2023-09-29 17:58 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-27 13:29 [PATCH] binfmt_elf_fdpic: clean up debug warnings Greg Ungerer
2023-09-27 15:59 ` Kees Cook
2023-09-28 4:53 ` Greg Ungerer
2023-09-29 17:58 ` Kees Cook [this message]
2023-09-29 17:58 ` Kees Cook
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