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SubjectRe: [PATCH] drivers: char: mem: Fix thinko in kmem address checks
Hi Robin,

[auto build test WARNING on char-misc/char-misc-testing]
[also build test WARNING on v4.10-rc2 next-20170104]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url: https://github.com/0day-ci/linux/commits/Robin-Murphy/drivers-char-mem-Fix-thinko-in-kmem-address-checks/20170104-235754
config: tile-allmodconfig (attached as .config)
compiler: tilegx-linux-gcc (GCC) 4.6.2
reproduce:
wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# save the attached .config to linux build tree
make.cross ARCH=tile

All warnings (new ones prefixed by >>):

drivers/char/mem.c: In function 'read_kmem':
>> drivers/char/mem.c:384:2: warning: passing argument 1 of 'kaddr_to_pfn' makes pointer from integer without a cast [enabled by default]
arch/tile/include/asm/page.h:281:29: note: expected 'const volatile void *' but argument is of type 'long unsigned int'
drivers/char/mem.c: In function 'write_kmem':
drivers/char/mem.c:515:2: warning: passing argument 1 of 'kaddr_to_pfn' makes pointer from integer without a cast [enabled by default]
arch/tile/include/asm/page.h:281:29: note: expected 'const volatile void *' but argument is of type 'long unsigned int'

vim +/kaddr_to_pfn +384 drivers/char/mem.c

368
369 vma->vm_pgoff = pfn;
370 return mmap_mem(file, vma);
371 }
372
373 /*
374 * This function reads the *virtual* memory as seen by the kernel.
375 */
376 static ssize_t read_kmem(struct file *file, char __user *buf,
377 size_t count, loff_t *ppos)
378 {
379 unsigned long p = *ppos;
380 ssize_t low_count, read, sz;
381 char *kbuf; /* k-addr because vread() takes vmlist_lock rwlock */
382 int err = 0;
383
> 384 if (!virt_addr_valid(p))
385 return -EIO;
386
387 read = 0;
388 if (p < (unsigned long) high_memory) {
389 low_count = count;
390 if (count > (unsigned long)high_memory - p)
391 low_count = (unsigned long)high_memory - p;
392

---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
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