fs/proc/vmcore.c:161:45: sparse: sparse: incorrect type in argument 1 (different address spaces)

[kernel test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   c5c17547b778975b3d83a73c8d84e8fb5ecf3ba5
commit: c1e63117711977cc4295b2ce73de29dd17066c82 proc/vmcore: fix clearing user buffer by properly using clear_user()
date:   6 days ago
config: powerpc-allmodconfig (https://download.01.org/0day-ci/archive/20211127/202111271335.2EUG3ljt-lkp@xxxxxxxxx/config)
compiler: powerpc-linux-gcc (GCC) 11.2.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # apt-get install sparse
        # sparse version: v0.6.4-dirty
        # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c1e63117711977cc4295b2ce73de29dd17066c82
        git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
        git fetch --no-tags linus master
        git checkout c1e63117711977cc4295b2ce73de29dd17066c82
        # save the config file to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' O=build_dir ARCH=powerpc SHELL=/bin/bash arch/powerpc/kernel/ fs/proc/

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


sparse warnings: (new ones prefixed by >>)
>> fs/proc/vmcore.c:161:45: sparse: sparse: incorrect type in argument 1 (different address spaces) @@     expected void [noderef] __user *addr @@     got char *buf @@
   fs/proc/vmcore.c:161:45: sparse:     expected void [noderef] __user *addr
   fs/proc/vmcore.c:161:45: sparse:     got char *buf

vim +161 fs/proc/vmcore.c

   133	
   134	/* Reads a page from the oldmem device from given offset. */
   135	ssize_t read_from_oldmem(char *buf, size_t count,
   136				 u64 *ppos, int userbuf,
   137				 bool encrypted)
   138	{
   139		unsigned long pfn, offset;
   140		size_t nr_bytes;
   141		ssize_t read = 0, tmp;
   142	
   143		if (!count)
   144			return 0;
   145	
   146		offset = (unsigned long)(*ppos % PAGE_SIZE);
   147		pfn = (unsigned long)(*ppos / PAGE_SIZE);
   148	
   149		down_read(&vmcore_cb_rwsem);
   150		do {
   151			if (count > (PAGE_SIZE - offset))
   152				nr_bytes = PAGE_SIZE - offset;
   153			else
   154				nr_bytes = count;
   155	
   156			/* If pfn is not ram, return zeros for sparse dump files */
   157			if (!pfn_is_ram(pfn)) {
   158				tmp = 0;
   159				if (!userbuf)
   160					memset(buf, 0, nr_bytes);
 > 161				else if (clear_user(buf, nr_bytes))
   162					tmp = -EFAULT;
   163			} else {
   164				if (encrypted)
   165					tmp = copy_oldmem_page_encrypted(pfn, buf,
   166									 nr_bytes,
   167									 offset,
   168									 userbuf);
   169				else
   170					tmp = copy_oldmem_page(pfn, buf, nr_bytes,
   171							       offset, userbuf);
   172			}
   173			if (tmp < 0) {
   174				up_read(&vmcore_cb_rwsem);
   175				return tmp;
   176			}
   177	
   178			*ppos += nr_bytes;
   179			count -= nr_bytes;
   180			buf += nr_bytes;
   181			read += nr_bytes;
   182			++pfn;
   183			offset = 0;
   184		} while (count);
   185	
   186		up_read(&vmcore_cb_rwsem);
   187		return read;
   188	}
   189	

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