binder: fix alloc->vma_vm_mm null-ptr dereference

{
  "id": "d2320f93fa2975f561b5a84d1a36232116fa49e5807bbbeae9cb7f4b12abf7c2",
  "url": "https://osv.dev/vulnerability/CVE-2022-49947",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "binder: fix alloc->vma_vm_mm null-ptr dereference",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: binder: fix alloc->vma_vm_mm null-ptr dereference Syzbot reported a couple issues introduced by commit 44e602b4e52f (\"binder_alloc: add missing mmap_lock calls when using the VMA\"), in which we attempt to acquire the mmap_lock when alloc->vma_vm_mm has not been initialized yet. This can happen if a binder_proc receives a transaction without having previously called mmap() to setup the binder_proc->alloc space in [1]. Also, a similar issue occurs via binder_alloc_print_pages() when we try to dump the debugfs binder stats file in [2]. Sample of syzbot's crash report: ================================================================== KASAN: null-ptr-deref in range [0x0000000000000128-0x000000000000012f] CPU: 0 PID: 3755 Comm: syz-executor229 Not tainted 6.0.0-rc1-next-20220819-syzkaller #0 syz-executor229[3755] cmdline: ./syz-executor2294415195 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022 RIP: 0010:__lock_acquire+0xd83/0x56d0 kernel/locking/lockdep.c:4923 [...] Call Trace: lock_acquire kernel/locking/lockdep.c:5666 [inline] lock_acquire+0x1ab/0x570 kernel/locking/lockdep.c:5631 down_read+0x98/0x450 kernel/locking/rwsem.c:1499 mmap_read_lock include/linux/mmap_lock.h:117 [inline] binder_alloc_new_buf_locked drivers/android/binder_alloc.c:405 [inline] binder_alloc_new_buf+0xa5/0x19e0 drivers/android/binder_alloc.c:593 binder_transaction+0x242e/0x9a80 drivers/android/bin",
    "evidence": "osv:CVE-2022-49947",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "5.15.66",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "5.19.8",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2022-49947",
      "aliases": [
        "CVE-2022-49947"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "577d9c05cc48c5242bcf719c06a5baf3105473ad"
                },
                {
                  "fixed": "81203ab7a6ef843a2b904a0a494f28c457d44d27"
                }
              ]
            },
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "7b0163c1b07b7ff1717aa975821c40df98786ddc"
                },
                {
                  "fixed": "b2a97babb0a510f8921891f9e70c5a5ef33cadac"
                }
              ]
            },
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "44e602b4e52f70f04620bbbf4fe46ecb40170bde"
                },
                {
                  "fixed": "1da52815d5f1b654c89044db0cdc6adce43da1f1"
                }
              ]
            }
          ],
          "versions": [
            "v5.15.65",
            "v5.15.64",
            "v5.19.7",
            "v5.19.6"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2022-49947.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.15.64"
                },
                {
                  "fixed": "5.15.66"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.19.6"
                },
                {
                  "fixed": "5.19.8"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2022-49947.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:33.299234462Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/1da52815d5f1b654c89044db0cdc6adce43da1f1",
        "https://git.kernel.org/stable/c/81203ab7a6ef843a2b904a0a494f28c457d44d27",
        "https://git.kernel.org/stable/c/b2a97babb0a510f8921891f9e70c5a5ef33cadac",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2022/49xxx/CVE-2022-49947.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2022-49947",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2022/49xxx/CVE-2022-49947.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2022-49947",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 500278,
  "published_at": "2025-06-18T11:00:11.012+00:00"
}