Re: [PATCH] usercopy: Check valid lifetime via stack depth

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

Hi Kees,

I love your patch! Yet something to improve:

[auto build test ERROR on hnaz-mm/master]
[also build test ERROR on kees/for-next/pstore v5.17-rc4 next-20220216]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Kees-Cook/usercopy-Check-valid-lifetime-via-stack-depth/20220217-041611
base:   https://github.com/hnaz/linux-mm master
config: openrisc-randconfig-r002-20220216 (https://download.01.org/0day-ci/archive/20220217/202202170844.jnpFFEmh-lkp@intel.com/config)
compiler: or1k-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://github.com/0day-ci/linux/commit/77944e5fa0cf5a29903b72466a22152c6a5d41ac
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Kees-Cook/usercopy-Check-valid-lifetime-via-stack-depth/20220217-041611
        git checkout 77944e5fa0cf5a29903b72466a22152c6a5d41ac
        # 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=openrisc SHELL=/bin/bash

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

All errors (new ones prefixed by >>):

   mm/usercopy.c: In function 'check_stack_object':
>> mm/usercopy.c:41:42: error: 'current_stack_pointer' undeclared (first use in this function); did you mean 'user_stack_pointer'?
      41 |         const void * const low = (void *)current_stack_pointer;
         |                                          ^~~~~~~~~~~~~~~~~~~~~
         |                                          user_stack_pointer
   mm/usercopy.c:41:42: note: each undeclared identifier is reported only once for each function it appears in
   mm/usercopy.c: In function '__check_object_size':
   mm/usercopy.c:287:41: error: 'current_stack_pointer' undeclared (first use in this function); did you mean 'user_stack_pointer'?
     287 |                                 (void *)current_stack_pointer - ptr,
         |                                         ^~~~~~~~~~~~~~~~~~~~~
         |                                         user_stack_pointer


vim +41 mm/usercopy.c

    24	
    25	/*
    26	 * Checks if a given pointer and length is contained by the current
    27	 * stack frame (if possible).
    28	 *
    29	 * Returns:
    30	 *	NOT_STACK: not at all on the stack
    31	 *	GOOD_FRAME: fully within a valid stack frame
    32	 *	GOOD_STACK: within the current stack (when can't frame-check exactly)
    33	 *	BAD_STACK: error condition (invalid stack position or bad stack frame)
    34	 */
    35	static noinline int check_stack_object(const void *obj, unsigned long len)
    36	{
    37		const void * const stack = task_stack_page(current);
    38		const void * const stackend = stack + THREAD_SIZE;
    39	#ifndef CONFIG_STACK_GROWSUP
    40		const void * const high = stackend;
  > 41		const void * const low = (void *)current_stack_pointer;
    42	#else
    43		const void * const high = (void *)current_stack_pointer;
    44		const void * const low = stack;
    45	#endif
    46		int ret;
    47	
    48		/* Object is not on the stack at all. */
    49		if (obj + len <= stack || stackend <= obj)
    50			return NOT_STACK;
    51	
    52		/*
    53		 * Reject: object partially overlaps the stack (passing the
    54		 * check above means at least one end is within the stack,
    55		 * so if this check fails, the other end is outside the stack).
    56		 */
    57		if (obj < stack || stackend < obj + len)
    58			return BAD_STACK;
    59	
    60		/* Check if object is safely within a valid frame. */
    61		ret = arch_within_stack_frames(stack, stackend, obj, len);
    62		if (ret)
    63			return ret;
    64	
    65		/*
    66		 * Reject: object not within current stack depth.
    67		 */
    68		if (obj < low || high < obj + len)
    69			return BAD_STACK;
    70	
    71		return GOOD_STACK;
    72	}
    73	

---
0-DAY CI Kernel Test Service, Intel Corporation
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