Hi Anmol, Thank you for the patch! Yet something to improve: [auto build test ERROR on staging/staging-testing] [also build test ERROR on v5.7-rc5 next-20200512] [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/Anmol/staging-android-ashmem-Fix... base: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git 1ff4388a06eb001efbc272754ef750c0b97817cb config: um-allmodconfig (attached as .config) compiler: gcc-7 (Ubuntu 7.5.0-6ubuntu2) 7.5.0 reproduce: # save the attached .config to linux build tree make ARCH=um If you fix the issue, kindly add following tag as appropriate Reported-by: kbuild test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): drivers/staging/android/ashmem.c: In function 'ashmem_mmap': vmfile_fops = *vmfile->f_op; ^ vmfile_fops.mmap = ashmem_vmfile_mmap; ^ 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 { 823a00202dabb1 Anmol 2020-05-13 370 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(a)google.com&gt; :::::: CC: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org