netfs: Only call folio_start_fscache() one time for each folio

{
  "id": "d97aa7ac19ab2c2cf15547f7cba0fb8c3d6e91f5ff2239f9b79dc2fe3f5423cf",
  "url": "https://osv.dev/vulnerability/CVE-2023-52582",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "netfs: Only call folio_start_fscache() one time for each folio",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: netfs: Only call folio_start_fscache() one time for each folio If a network filesystem using netfs implements a clamp_length() function, it can set subrequest lengths smaller than a page size. When we loop through the folios in netfs_rreq_unlock_folios() to set any folios to be written back, we need to make sure we only call folio_start_fscache() once for each folio. Otherwise, this simple testcase: mount -o fsc,rsize=1024,wsize=1024 127.0.0.1:/export /mnt/nfs dd if=/dev/zero of=/mnt/nfs/file.bin bs=4096 count=1 1+0 records in 1+0 records out 4096 bytes (4.1 kB, 4.0 KiB) copied, 0.0126359 s, 324 kB/s echo 3 > /proc/sys/vm/drop_caches cat /mnt/nfs/file.bin > /dev/null will trigger an oops similar to the following: page dumped because: VM_BUG_ON_FOLIO(folio_test_private_2(folio)) ------------[ cut here ]------------ kernel BUG at include/linux/netfs.h:44! ... CPU: 5 PID: 134 Comm: kworker/u16:5 Kdump: loaded Not tainted 6.4.0-rc5 ... RIP: 0010:netfs_rreq_unlock_folios+0x68e/0x730 [netfs] ... Call Trace: netfs_rreq_assess+0x497/0x660 [netfs] netfs_subreq_terminated+0x32b/0x610 [netfs] nfs_netfs_read_completion+0x14e/0x1a0 [nfs] nfs_read_completion+0x2f9/0x330 [nfs] rpc_free_task+0x72/0xa0 [sunrpc] rpc_async_release+0x46/0x70 [sunrpc] process_one_work+0x3bd/0x710 worker_thread+0x89/0x610 kthread+0x181/0x1c0 ret_from_fork+0x29/0x50",
    "evidence": "osv:CVE-2023-52582",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.1.56",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.5.6",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2023-52582",
      "aliases": [
        "CVE-2023-52582"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "3d3c95046742e4eebaa4b891b0b01cbbed94ebbd"
                },
                {
                  "fixed": "df9950d37df113db59495fa09d060754366a2b7c"
                },
                {
                  "fixed": "d9f5537479d4ec97ea92ff24e81a517d5772581a"
                },
                {
                  "fixed": "df1c357f25d808e30b216188330e708e09e1a412"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2023-52582.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.13.0"
                },
                {
                  "fixed": "6.1.56"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.2.0"
                },
                {
                  "fixed": "6.5.6"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2023-52582.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:42.442208750Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/d9f5537479d4ec97ea92ff24e81a517d5772581a",
        "https://git.kernel.org/stable/c/df1c357f25d808e30b216188330e708e09e1a412",
        "https://git.kernel.org/stable/c/df9950d37df113db59495fa09d060754366a2b7c",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/52xxx/CVE-2023-52582.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2023-52582",
        "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/2023/52xxx/CVE-2023-52582.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2023-52582",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 509797,
  "published_at": "2024-03-02T21:59:48.49+00:00"
}