Re: [PATCH v5] mm: Optional full ASLR for mmap(), mremap(), vdso and stack

[kernel test robot <lkp@intel.com>]

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Hi Topi,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on aae5ab854e38151e69f261dbf0e3b7e396403178]

url:    https://github.com/0day-ci/linux/commits/Topi-Miettinen/mm-Optional-full-ASLR-for-mmap-mremap-vdso-and-stack/20201130-051703
base:    aae5ab854e38151e69f261dbf0e3b7e396403178
config: x86_64-randconfig-a002-20201130 (attached as .config)
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project f502b14d40e751fe00afc493ef0d08f196524886)
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
        # install x86_64 cross compiling tool for clang build
        # apt-get install binutils-x86-64-linux-gnu
        # https://github.com/0day-ci/linux/commit/c06384c5cecf700db214c69a4565c41a4c4fad82
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Topi-Miettinen/mm-Optional-full-ASLR-for-mmap-mremap-vdso-and-stack/20201130-051703
        git checkout c06384c5cecf700db214c69a4565c41a4c4fad82
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

   arch/x86/entry/vdso/vma.c:38:19: warning: no previous prototype for function 'arch_get_vdso_data' [-Wmissing-prototypes]
   struct vdso_data *arch_get_vdso_data(void *vvar_page)
                     ^
   arch/x86/entry/vdso/vma.c:38:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   struct vdso_data *arch_get_vdso_data(void *vvar_page)
   ^
   static 
>> arch/x86/entry/vdso/vma.c:382:9: warning: cast to 'void *' from smaller integer type 'int' [-Wint-to-void-pointer-cast]
                           if (!IS_ERR_VALUE(ret))
                                ^~~~~~~~~~~~~~~~~
   include/linux/err.h:22:49: note: expanded from macro 'IS_ERR_VALUE'
   #define IS_ERR_VALUE(x) unlikely((unsigned long)(void *)(x) >= (unsigned long)-MAX_ERRNO)
                           ~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/compiler.h:48:41: note: expanded from macro 'unlikely'
   #  define unlikely(x)   (__branch_check__(x, 0, __builtin_constant_p(x)))
                            ~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/compiler.h:33:34: note: expanded from macro '__branch_check__'
                           ______r = __builtin_expect(!!(x), expect);      \
                                                         ^
>> arch/x86/entry/vdso/vma.c:382:9: warning: cast to 'void *' from smaller integer type 'int' [-Wint-to-void-pointer-cast]
                           if (!IS_ERR_VALUE(ret))
                                ^~~~~~~~~~~~~~~~~
   include/linux/err.h:22:49: note: expanded from macro 'IS_ERR_VALUE'
   #define IS_ERR_VALUE(x) unlikely((unsigned long)(void *)(x) >= (unsigned long)-MAX_ERRNO)
                           ~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/compiler.h:48:68: note: expanded from macro 'unlikely'
   #  define unlikely(x)   (__branch_check__(x, 0, __builtin_constant_p(x)))
                            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
   include/linux/compiler.h:35:19: note: expanded from macro '__branch_check__'
                                                expect, is_constant);      \
                                                        ^~~~~~~~~~~
   3 warnings generated.

vim +382 arch/x86/entry/vdso/vma.c

   364	
   365	static int map_vdso_randomized(const struct vdso_image *image)
   366	{
   367		unsigned long addr;
   368	
   369		if (randomize_va_space == 3) {
   370			/*
   371			 * Randomize vdso address.
   372			 */
   373			int i = MAX_RANDOM_VDSO_RETRIES;
   374	
   375			do {
   376				int ret;
   377	
   378				/* Try a few times to find a free area */
   379				addr = arch_mmap_rnd();
   380	
   381				ret = map_vdso(image, addr);
 > 382				if (!IS_ERR_VALUE(ret))
   383					return ret;
   384			} while (--i >= 0);
   385	
   386			/* Give up and try the less random way */
   387		}
   388		addr = vdso_addr(current->mm->start_stack, image->size-image->sym_vvar_start);
   389	
   390		return map_vdso(image, addr);
   391	}
   392	#endif
   393	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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