Re: [PATCH] taging: android: ashmem: Declared const key

kbuild test robot
2020-04-11T20:44:48Z

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Hi MugilRaj,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on staging/staging-testing]
[also build test ERROR on v5.6 next-20200411]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url: https://github.com/0day-ci/linux/commits/MugilRaj/taging-android-ashmem-Declared-const-key/20200412-033150
base: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git 134c0700a05174f2520d51ba4dd95698ffa779de
config: alpha-allmodconfig (attached as .config)
compiler: alpha-linux-gcc (GCC) 9.3.0
reproduce:
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# save the attached .config to linux build tree
GCC_VERSION=9.3.0 make.cross ARCH=alpha

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

All errors (new ones prefixed by >>):

drivers/staging/android/ashmem.c: In function 'ashmem_mmap':
>> drivers/staging/android/ashmem.c:418:16: error: assignment of read-only variable 'vmfile_fops'
418 | vmfile_fops = *vmfile->f_op;
| ^
>> drivers/staging/android/ashmem.c:419:21: error: assignment of member 'mmap' in read-only object
419 | vmfile_fops.mmap = ashmem_vmfile_mmap;
| ^
>> drivers/staging/android/ashmem.c:420:34: error: assignment of member 'get_unmapped_area' in read-only object
420 | vmfile_fops.get_unmapped_area =
| ^

vim +/vmfile_fops +418 drivers/staging/android/ashmem.c

6d67b0290b4b84 Suren Baghdasaryan 2020-01-27 367
11980c2ac4ccfa Robert Love 2011-12-20 368 static int ashmem_mmap(struct file *file, struct vm_area_struct *vma)
11980c2ac4ccfa Robert Love 2011-12-20 369 {
d5d1ae9cc69f62 mugil2301 2020-04-12 370 static const struct file_operations vmfile_fops;
11980c2ac4ccfa Robert Love 2011-12-20 371 struct ashmem_area *asma = file->private_data;
11980c2ac4ccfa Robert Love 2011-12-20 372 int ret = 0;
11980c2ac4ccfa Robert Love 2011-12-20 373
11980c2ac4ccfa Robert Love 2011-12-20 374 mutex_lock(&ashmem_mutex);
11980c2ac4ccfa Robert Love 2011-12-20 375
11980c2ac4ccfa Robert Love 2011-12-20 376 /* user needs to SET_SIZE before mapping */
59848d6aded59a Alistair Strachan 2018-06-19 377 if (!asma->size) {
11980c2ac4ccfa Robert Love 2011-12-20 378 ret = -EINVAL;
11980c2ac4ccfa Robert Love 2011-12-20 379 goto out;
11980c2ac4ccfa Robert Love 2011-12-20 380 }
11980c2ac4ccfa Robert Love 2011-12-20 381
8632c614565d0c Alistair Strachan 2018-06-19 382 /* requested mapping size larger than object size */
8632c614565d0c Alistair Strachan 2018-06-19 383 if (vma->vm_end - vma->vm_start > PAGE_ALIGN(asma->size)) {
11980c2ac4ccfa Robert Love 2011-12-20 384 ret = -EINVAL;
11980c2ac4ccfa Robert Love 2011-12-20 385 goto out;
11980c2ac4ccfa Robert Love 2011-12-20 386 }
11980c2ac4ccfa Robert Love 2011-12-20 387
11980c2ac4ccfa Robert Love 2011-12-20 388 /* requested protection bits must match our allowed protection mask */
59848d6aded59a Alistair Strachan 2018-06-19 389 if ((vma->vm_flags & ~calc_vm_prot_bits(asma->prot_mask, 0)) &
59848d6aded59a Alistair Strachan 2018-06-19 390 calc_vm_prot_bits(PROT_MASK, 0)) {
11980c2ac4ccfa Robert Love 2011-12-20 391 ret = -EPERM;
11980c2ac4ccfa Robert Love 2011-12-20 392 goto out;
11980c2ac4ccfa Robert Love 2011-12-20 393 }
56f76fc68492af Arve Hjønnevåg 2011-12-20 394 vma->vm_flags &= ~calc_vm_may_flags(~asma->prot_mask);
11980c2ac4ccfa Robert Love 2011-12-20 395
11980c2ac4ccfa Robert Love 2011-12-20 396 if (!asma->file) {
11980c2ac4ccfa Robert Love 2011-12-20 397 char *name = ASHMEM_NAME_DEF;
11980c2ac4ccfa Robert Love 2011-12-20 398 struct file *vmfile;
11980c2ac4ccfa Robert Love 2011-12-20 399
11980c2ac4ccfa Robert Love 2011-12-20 400 if (asma->name[ASHMEM_NAME_PREFIX_LEN] != '\0')
11980c2ac4ccfa Robert Love 2011-12-20 401 name = asma->name;
11980c2ac4ccfa Robert Love 2011-12-20 402
11980c2ac4ccfa Robert Love 2011-12-20 403 /* ... and allocate the backing shmem file */
11980c2ac4ccfa Robert Love 2011-12-20 404 vmfile = shmem_file_setup(name, asma->size, vma->vm_flags);
7f44cb0ba88b40 Viresh Kumar 2015-07-31 405 if (IS_ERR(vmfile)) {
11980c2ac4ccfa Robert Love 2011-12-20 406 ret = PTR_ERR(vmfile);
11980c2ac4ccfa Robert Love 2011-12-20 407 goto out;
11980c2ac4ccfa Robert Love 2011-12-20 408 }
97fbfef6bd5978 Shuxiao Zhang 2017-04-06 409 vmfile->f_mode |= FMODE_LSEEK;
11980c2ac4ccfa Robert Love 2011-12-20 410 asma->file = vmfile;
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27 411 /*
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27 412 * override mmap operation of the vmfile so that it can't be
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27 413 * remapped which would lead to creation of a new vma with no
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27 414 * asma permission checks. Have to override get_unmapped_area
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27 415 * as well to prevent VM_BUG_ON check for f_ops modification.
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27 416 */
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27 417 if (!vmfile_fops.mmap) {
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27 @418 vmfile_fops = *vmfile->f_op;
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27 @419 vmfile_fops.mmap = ashmem_vmfile_mmap;
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27 @420 vmfile_fops.get_unmapped_area =
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27 421 ashmem_vmfile_get_unmapped_area;
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27 422 }
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27 423 vmfile->f_op = &vmfile_fops;
11980c2ac4ccfa Robert Love 2011-12-20 424 }
11980c2ac4ccfa Robert Love 2011-12-20 425 get_file(asma->file);
11980c2ac4ccfa Robert Love 2011-12-20 426
11980c2ac4ccfa Robert Love 2011-12-20 427 /*
11980c2ac4ccfa Robert Love 2011-12-20 428 * XXX - Reworked to use shmem_zero_setup() instead of
11980c2ac4ccfa Robert Love 2011-12-20 429 * shmem_set_file while we're in staging. -jstultz
11980c2ac4ccfa Robert Love 2011-12-20 430 */
11980c2ac4ccfa Robert Love 2011-12-20 431 if (vma->vm_flags & VM_SHARED) {
11980c2ac4ccfa Robert Love 2011-12-20 432 ret = shmem_zero_setup(vma);
11980c2ac4ccfa Robert Love 2011-12-20 433 if (ret) {
11980c2ac4ccfa Robert Love 2011-12-20 434 fput(asma->file);
11980c2ac4ccfa Robert Love 2011-12-20 435 goto out;
11980c2ac4ccfa Robert Love 2011-12-20 436 }
44960f2a7b63e2 John Stultz 2018-07-31 437 } else {
44960f2a7b63e2 John Stultz 2018-07-31 438 vma_set_anonymous(vma);
11980c2ac4ccfa Robert Love 2011-12-20 439 }
11980c2ac4ccfa Robert Love 2011-12-20 440
11980c2ac4ccfa Robert Love 2011-12-20 441 if (vma->vm_file)
11980c2ac4ccfa Robert Love 2011-12-20 442 fput(vma->vm_file);
11980c2ac4ccfa Robert Love 2011-12-20 443 vma->vm_file = asma->file;
11980c2ac4ccfa Robert Love 2011-12-20 444
11980c2ac4ccfa Robert Love 2011-12-20 445 out:
11980c2ac4ccfa Robert Love 2011-12-20 446 mutex_unlock(&ashmem_mutex);
11980c2ac4ccfa Robert Love 2011-12-20 447 return ret;
11980c2ac4ccfa Robert Love 2011-12-20 448 }
11980c2ac4ccfa Robert Love 2011-12-20 449

:::::: The code at line 418 was first introduced by commit
:::::: 6d67b0290b4b84c477e6a2fc6e005e174d3c7786 staging: android: ashmem: Disallow ashmem memory from being remapped

:::::: TO: Suren Baghdasaryan <surenb@google.com>
:::::: CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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