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Message-ID: <202204181515.FC6649DC81@keescook>
Date: Mon, 18 Apr 2022 15:25:47 -0700
From: Kees Cook <keescook@...omium.org>
To: Dan Li <ashimida@...ux.alibaba.com>
Cc: kbuild-all@...ts.01.org, linux-kernel@...r.kernel.org,
kernel test robot <lkp@...el.com>
Subject: Re: [kees:for-next/lkdtm 6/6] drivers/misc/lkdtm/cfi.c:62:37:
warning: cast from pointer to integer of different size
On Sun, Apr 17, 2022 at 07:26:33AM +0800, kernel test robot wrote:
> tree: https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git for-next/lkdtm
> head: 2e53b877dc1258d4ac3de98f496bb88ec3bf5e25
> commit: 2e53b877dc1258d4ac3de98f496bb88ec3bf5e25 [6/6] lkdtm: Add CFI_BACKWARD to test ROP mitigations
> config: sparc-randconfig-r026-20220417 (https://download.01.org/0day-ci/archive/20220417/202204170710.LwCV5Ec0-lkp@intel.com/config)
> compiler: sparc-linux-gcc (GCC) 11.2.0
> reproduce (this is a W=1 build):
> wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
> chmod +x ~/bin/make.cross
> # https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git/commit/?id=2e53b877dc1258d4ac3de98f496bb88ec3bf5e25
> git remote add kees https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git
> git fetch --no-tags kees for-next/lkdtm
> git checkout 2e53b877dc1258d4ac3de98f496bb88ec3bf5e25
> # save the config file to linux build tree
> mkdir build_dir
> COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=sparc SHELL=/bin/bash drivers/misc/lkdtm/
>
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@...el.com>
>
> All warnings (new ones prefixed by >>):
>
> drivers/misc/lkdtm/cfi.c: In function 'set_return_addr_unchecked':
> >> drivers/misc/lkdtm/cfi.c:62:37: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
> 62 | ((__force __typeof__(addr))((__force u64)(addr) | PAGE_OFFSET))
> | ^
> drivers/misc/lkdtm/cfi.c:72:13: note: in expansion of macro 'no_pac_addr'
> 72 | if (no_pac_addr(*ret_addr) == expected)
> | ^~~~~~~~~~~
Hmm. I don't see why this is warning. The macro looks like untagged_addr():
#define untagged_addr(addr) ({ \
u64 __addr = (__force u64)(addr); \
__addr &= __untagged_addr(__addr); \
(__force __typeof__(addr))__addr; \
})
--
Kees Cook
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