{
   "containers": {
      "cna": {
         "providerMetadata": {
            "orgId": "f4215fc3-5b6b-47ff-a258-f7189bd81038"
         },
         "descriptions": [
            {
               "lang": "en",
               "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/msm: Fix mmap to include VM_IO and VM_DONTDUMP\n\nIn commit 510410bfc034 (\"drm/msm: Implement mmap as GEM object\nfunction\") we switched to a new/cleaner method of doing things. That's\ngood, but we missed a little bit.\n\nBefore that commit, we used to _first_ run through the\ndrm_gem_mmap_obj() case where `obj->funcs->mmap()` was NULL. That meant\nthat we ran:\n\n  vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;\n  vma->vm_page_prot = pgprot_writecombine(vm_get_page_prot(vma->vm_flags));\n  vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot);\n\n...and _then_ we modified those mappings with our own. Now that\n`obj->funcs->mmap()` is no longer NULL we don't run the default\ncode. It looks like the fact that the vm_flags got VM_IO / VM_DONTDUMP\nwas important because we're now getting crashes on Chromebooks that\nuse ARC++ while logging out. Specifically a crash that looks like this\n(this is on a 5.10 kernel w/ relevant backports but also seen on a\n5.15 kernel):\n\n  Unable to handle kernel paging request at virtual address ffffffc008000000\n  Mem abort info:\n    ESR = 0x96000006\n    EC = 0x25: DABT (current EL), IL = 32 bits\n    SET = 0, FnV = 0\n    EA = 0, S1PTW = 0\n  Data abort info:\n    ISV = 0, ISS = 0x00000006\n    CM = 0, WnR = 0\n  swapper pgtable: 4k pages, 39-bit VAs, pgdp=000000008293d000\n  [ffffffc008000000] pgd=00000001002b3003, p4d=00000001002b3003,\n                     pud=00000001002b3003, pmd=0000000000000000\n  Internal error: Oops: 96000006 [#1] PREEMPT SMP\n  [...]\n  CPU: 7 PID: 15734 Comm: crash_dump64 Tainted: G W 5.10.67 #1 [...]\n  Hardware name: Qualcomm Technologies, Inc. sc7280 IDP SKU2 platform (DT)\n  pstate: 80400009 (Nzcv daif +PAN -UAO -TCO BTYPE=--)\n  pc : __arch_copy_to_user+0xc0/0x30c\n  lr : copyout+0xac/0x14c\n  [...]\n  Call trace:\n   __arch_copy_to_user+0xc0/0x30c\n   copy_page_to_iter+0x1a0/0x294\n   process_vm_rw_core+0x240/0x408\n   process_vm_rw+0x110/0x16c\n   __arm64_sys_process_vm_readv+0x30/0x3c\n   el0_svc_common+0xf8/0x250\n   do_el0_svc+0x30/0x80\n   el0_svc+0x10/0x1c\n   el0_sync_handler+0x78/0x108\n   el0_sync+0x184/0x1c0\n  Code: f8408423 f80008c3 910020c6 36100082 (b8404423)\n\nLet's add the two flags back in.\n\nWhile we're at it, the fact that we aren't running the default means\nthat we _don't_ need to clear out VM_PFNMAP, so remove that and save\nan instruction.\n\nNOTE: it was confirmed that VM_IO was the important flag to fix the\nproblem I was seeing, but adding back VM_DONTDUMP seems like a sane\nthing to do so I'm doing that too."
            }
         ],
         "affected": [
            {
               "product": "Linux",
               "vendor": "Linux",
               "defaultStatus": "unaffected",
               "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
               "programFiles": [
                  "drivers/gpu/drm/msm/msm_gem.c"
               ],
               "versions": [
                  {
                     "version": "510410bfc034",
                     "lessThan": "8e2b7fe5e8a4",
                     "status": "affected",
                     "versionType": "git"
                  },
                  {
                     "version": "510410bfc034",
                     "lessThan": "3466d9e217b3",
                     "status": "affected",
                     "versionType": "git"
                  }
               ]
            },
            {
               "product": "Linux",
               "vendor": "Linux",
               "defaultStatus": "affected",
               "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
               "programFiles": [
                  "drivers/gpu/drm/msm/msm_gem.c"
               ],
               "versions": [
                  {
                     "version": "5.15",
                     "status": "affected"
                  },
                  {
                     "version": "0",
                     "lessThan": "5.15",
                     "status": "unaffected",
                     "versionType": "custom"
                  },
                  {
                     "version": "5.15.7",
                     "lessThanOrEqual": "5.15.*",
                     "status": "unaffected",
                     "versionType": "custom"
                  },
                  {
                     "version": "5.16",
                     "lessThanOrEqual": "*",
                     "status": "unaffected",
                     "versionType": "original_commit_for_fix"
                  }
               ]
            }
         ],
         "references": [
            {
               "url": "https://git.kernel.org/stable/c/8e2b7fe5e8a4be5e571561d9afcfbd92097288ba"
            },
            {
               "url": "https://git.kernel.org/stable/c/3466d9e217b337bf473ee629c608e53f9f3ab786"
            }
         ],
         "title": "drm/msm: Fix mmap to include VM_IO and VM_DONTDUMP",
         "x_generator": {
            "engine": "bippy-a5840b7849dd"
         }
      }
   },
   "cveMetadata": {
      "assignerOrgId": "f4215fc3-5b6b-47ff-a258-f7189bd81038",
      "cveID": "CVE-2021-47531",
      "requesterUserId": "gregkh@kernel.org",
      "serial": "1",
      "state": "PUBLISHED"
   },
   "dataType": "CVE_RECORD",
   "dataVersion": "5.0"
}