CVE-2025-38139 (GCVE-0-2025-38139)
Vulnerability from cvelistv5
Published
2025-07-03 08:35
Modified
2026-08-05 11:59
Severity ?
9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: netfs: Fix oops in write-retry from mis-resetting the subreq iterator Fix the resetting of the subrequest iterator in netfs_retry_write_stream() to use the iterator-reset function as the iterator may have been shortened by a previous retry. In such a case, the amount of data to be written by the subrequest is not "subreq->len" but "subreq->len - subreq->transferred". Without this, KASAN may see an error in iov_iter_revert(): BUG: KASAN: slab-out-of-bounds in iov_iter_revert lib/iov_iter.c:633 [inline] BUG: KASAN: slab-out-of-bounds in iov_iter_revert+0x443/0x5a0 lib/iov_iter.c:611 Read of size 4 at addr ffff88802912a0b8 by task kworker/u32:7/1147 CPU: 1 UID: 0 PID: 1147 Comm: kworker/u32:7 Not tainted 6.15.0-rc6-syzkaller-00052-g9f35e33144ae #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Workqueue: events_unbound netfs_write_collection_worker Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:408 [inline] print_report+0xc3/0x670 mm/kasan/report.c:521 kasan_report+0xe0/0x110 mm/kasan/report.c:634 iov_iter_revert lib/iov_iter.c:633 [inline] iov_iter_revert+0x443/0x5a0 lib/iov_iter.c:611 netfs_retry_write_stream fs/netfs/write_retry.c:44 [inline] netfs_retry_writes+0x166d/0x1a50 fs/netfs/write_retry.c:231 netfs_collect_write_results fs/netfs/write_collect.c:352 [inline] netfs_write_collection_worker+0x23fd/0x3830 fs/netfs/write_collect.c:374 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3238 process_scheduled_works kernel/workqueue.c:3319 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400 kthread+0x3c2/0x780 kernel/kthread.c:464 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 </TASK>
References
Impacted products
Vendor Product Version
Linux Linux Version: cd0277ed0c188dd40e7744e89299af7b78831ca4
Version: cd0277ed0c188dd40e7744e89299af7b78831ca4
Version: cd0277ed0c188dd40e7744e89299af7b78831ca4
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/netfs/write_retry.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "e0fefe9bc07e6101fdc57abda3644f296c114e31",
              "status": "affected",
              "version": "cd0277ed0c188dd40e7744e89299af7b78831ca4",
              "versionType": "git"
            },
            {
              "lessThan": "bd0edaf99a920b1a9decd773179caacacb61d0fd",
              "status": "affected",
              "version": "cd0277ed0c188dd40e7744e89299af7b78831ca4",
              "versionType": "git"
            },
            {
              "lessThan": "4481f7f2b3df123ec77e828c849138f75cff2bf2",
              "status": "affected",
              "version": "cd0277ed0c188dd40e7744e89299af7b78831ca4",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/netfs/write_retry.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.12"
            },
            {
              "lessThan": "6.12",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.37",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.15.*",
              "status": "unaffected",
              "version": "6.15.3",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.16",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.37",
                  "versionStartIncluding": "6.12",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.15.3",
                  "versionStartIncluding": "6.12",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.16",
                  "versionStartIncluding": "6.12",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfs: Fix oops in write-retry from mis-resetting the subreq iterator\n\nFix the resetting of the subrequest iterator in netfs_retry_write_stream()\nto use the iterator-reset function as the iterator may have been shortened\nby a previous retry.  In such a case, the amount of data to be written by\nthe subrequest is not \"subreq-\u003elen\" but \"subreq-\u003elen -\nsubreq-\u003etransferred\".\n\nWithout this, KASAN may see an error in iov_iter_revert():\n\n   BUG: KASAN: slab-out-of-bounds in iov_iter_revert lib/iov_iter.c:633 [inline]\n   BUG: KASAN: slab-out-of-bounds in iov_iter_revert+0x443/0x5a0 lib/iov_iter.c:611\n   Read of size 4 at addr ffff88802912a0b8 by task kworker/u32:7/1147\n\n   CPU: 1 UID: 0 PID: 1147 Comm: kworker/u32:7 Not tainted 6.15.0-rc6-syzkaller-00052-g9f35e33144ae #0 PREEMPT(full)\n   Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014\n   Workqueue: events_unbound netfs_write_collection_worker\n   Call Trace:\n    \u003cTASK\u003e\n    __dump_stack lib/dump_stack.c:94 [inline]\n    dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120\n    print_address_description mm/kasan/report.c:408 [inline]\n    print_report+0xc3/0x670 mm/kasan/report.c:521\n    kasan_report+0xe0/0x110 mm/kasan/report.c:634\n    iov_iter_revert lib/iov_iter.c:633 [inline]\n    iov_iter_revert+0x443/0x5a0 lib/iov_iter.c:611\n    netfs_retry_write_stream fs/netfs/write_retry.c:44 [inline]\n    netfs_retry_writes+0x166d/0x1a50 fs/netfs/write_retry.c:231\n    netfs_collect_write_results fs/netfs/write_collect.c:352 [inline]\n    netfs_write_collection_worker+0x23fd/0x3830 fs/netfs/write_collect.c:374\n    process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3238\n    process_scheduled_works kernel/workqueue.c:3319 [inline]\n    worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400\n    kthread+0x3c2/0x780 kernel/kthread.c:464\n    ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153\n    ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245\n    \u003c/TASK\u003e"
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.8,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The trigger is entirely under the control of the remote 9p server, which drives the retry path by reporting short byte counts in its RWRITE replies; the 9p client supports trans=tcp/trans=rdma to a remote peer and the protocol is unauthenticated and unencrypted by default, so an on-path attacker can inject the same replies.\nAC:L - Exploitation is fully deterministic \u2014 the server simply answers two consecutive TWRITEs on the same subrequest with a partial count, and the second retry over-reverts the iterator by an attacker-chosen amount; there is no race, timing window, or uncontrollable memory-layout precondition.\nPR:N - The malicious or compromised 9p server (or an on-path attacker on plaintext 9p/TCP) holds no credentials on the victim client, and 9p mounts are typically established with no authentication at all.\nUI:N - No per-instance victim action is needed: on an existing 9p mount, ordinary file writes and background writeback from the kworker reach the retry path, and the server alone decides when to emit the short write that arms it.\nS:U - The out-of-bounds access and the resulting corrupted iterator stay within the kernel\u0027s own security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - iov_iter_revert() reads out of bounds backwards off the kvmalloc\u0027d bvec array (or off the head of the folio_queue chain) by an attacker-chosen distance, and the resulting forged bio_vec makes the client transmit memory pointed to by an adjacent-heap page pointer straight to the attacker-controlled server, yielding arbitrary kernel memory disclosure.\nI:H - The corrupted iterator carries bv_page/bv_len values sourced from attacker-groomable adjacent heap memory (or a stale/freed folio_queue), so subsequent I/O submission and page reference get/put operate on arbitrary struct page pointers, giving refcount corruption and a path to control-flow hijack.\nA:H - The bug is a confirmed oops \u2014 syzbot reproduced a KASAN slab-out-of-bounds in iov_iter_revert() from netfs_write_collection_worker, and the unbounded backwards walk readily runs off the slab or dereferences a NULL folioq-\u003eprev, panicking the kernel."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T11:59:50.138Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/e0fefe9bc07e6101fdc57abda3644f296c114e31"
        },
        {
          "url": "https://git.kernel.org/stable/c/bd0edaf99a920b1a9decd773179caacacb61d0fd"
        },
        {
          "url": "https://git.kernel.org/stable/c/4481f7f2b3df123ec77e828c849138f75cff2bf2"
        }
      ],
      "title": "netfs: Fix oops in write-retry from mis-resetting the subreq iterator",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-38139",
    "datePublished": "2025-07-03T08:35:41.271Z",
    "dateReserved": "2025-04-16T04:51:23.987Z",
    "dateUpdated": "2026-08-05T11:59:50.138Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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