Re: [PATCH v3 1/2] userfaultfd: do not untag user pointers

Hi Peter,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on arm64/for-next/core]
[also build test WARNING on kselftest/next linus/master v5.13 next-20210701]
[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/Peter-Collingbourne/userfaultfd-do-not-untag-user-pointers/20210703-065801
base:   https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-next/core
config: openrisc-randconfig-c004-20210702 (attached as .config)
compiler: or1k-linux-gcc (GCC) 9.3.0
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/42177546697fa573571799dc11ecd12a65449886
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Peter-Collingbourne/userfaultfd-do-not-untag-user-pointers/20210703-065801
        git checkout 42177546697fa573571799dc11ecd12a65449886
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=openrisc 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <redacted>

All warnings (new ones prefixed by >>):

   fs/userfaultfd.c: In function 'userfaultfd_writeprotect':

quoted

fs/userfaultfd.c:1816:32: warning: passing argument 2 of 'validate_range' makes integer from pointer without a cast [-Wint-conversion]

    1816 |  ret = validate_range(ctx->mm, &uffdio_wp.range.start,
         |                                ^~~~~~~~~~~~~~~~~~~~~~
         |                                |
         |                                __u64 * {aka long long unsigned int *}
   fs/userfaultfd.c:1239:14: note: expected '__u64' {aka 'long long unsigned int'} but argument is of type '__u64 *' {aka 'long long unsigned int *'}
    1239 |        __u64 start, __u64 len)
         |        ~~~~~~^~~~~
   fs/userfaultfd.c: In function 'userfaultfd_continue':
   fs/userfaultfd.c:1864:32: warning: passing argument 2 of 'validate_range' makes integer from pointer without a cast [-Wint-conversion]
    1864 |  ret = validate_range(ctx->mm, &uffdio_continue.range.start,
         |                                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
         |                                |
         |                                __u64 * {aka long long unsigned int *}
   fs/userfaultfd.c:1239:14: note: expected '__u64' {aka 'long long unsigned int'} but argument is of type '__u64 *' {aka 'long long unsigned int *'}
    1239 |        __u64 start, __u64 len)
         |        ~~~~~~^~~~~


vim +/validate_range +1816 fs/userfaultfd.c

ad465cae96b456 Andrea Arcangeli 2015-09-04  1797  
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1798  static int userfaultfd_writeprotect(struct userfaultfd_ctx *ctx,
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1799  				    unsigned long arg)
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1800  {
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1801  	int ret;
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1802  	struct uffdio_writeprotect uffdio_wp;
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1803  	struct uffdio_writeprotect __user *user_uffdio_wp;
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1804  	struct userfaultfd_wake_range range;
23080e2783ba45 Peter Xu         2020-04-06  1805  	bool mode_wp, mode_dontwake;
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1806  
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1807  	if (READ_ONCE(ctx->mmap_changing))
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1808  		return -EAGAIN;
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1809  
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1810  	user_uffdio_wp = (struct uffdio_writeprotect __user *) arg;
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1811  
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1812  	if (copy_from_user(&uffdio_wp, user_uffdio_wp,
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1813  			   sizeof(struct uffdio_writeprotect)))
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1814  		return -EFAULT;
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1815  
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06 @1816  	ret = validate_range(ctx->mm, &uffdio_wp.range.start,
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1817  			     uffdio_wp.range.len);
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1818  	if (ret)
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1819  		return ret;
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1820  
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1821  	if (uffdio_wp.mode & ~(UFFDIO_WRITEPROTECT_MODE_DONTWAKE |
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1822  			       UFFDIO_WRITEPROTECT_MODE_WP))
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1823  		return -EINVAL;
23080e2783ba45 Peter Xu         2020-04-06  1824  
23080e2783ba45 Peter Xu         2020-04-06  1825  	mode_wp = uffdio_wp.mode & UFFDIO_WRITEPROTECT_MODE_WP;
23080e2783ba45 Peter Xu         2020-04-06  1826  	mode_dontwake = uffdio_wp.mode & UFFDIO_WRITEPROTECT_MODE_DONTWAKE;
23080e2783ba45 Peter Xu         2020-04-06  1827  
23080e2783ba45 Peter Xu         2020-04-06  1828  	if (mode_wp && mode_dontwake)
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1829  		return -EINVAL;
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1830  
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1831  	ret = mwriteprotect_range(ctx->mm, uffdio_wp.range.start,
23080e2783ba45 Peter Xu         2020-04-06  1832  				  uffdio_wp.range.len, mode_wp,
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1833  				  &ctx->mmap_changing);
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1834  	if (ret)
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1835  		return ret;
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1836  
23080e2783ba45 Peter Xu         2020-04-06  1837  	if (!mode_wp && !mode_dontwake) {
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1838  		range.start = uffdio_wp.range.start;
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1839  		range.len = uffdio_wp.range.len;
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1840  		wake_userfault(ctx, &range);
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1841  	}
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1842  	return ret;
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1843  }
63b2d4174c4ad1 Andrea Arcangeli 2020-04-06  1844  

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