Linux Distros 未修補弱點：CVE-2026-63894
high Nessus Plugin ID 328203
語言:
概要
Linux/Unix 主機上安裝的一個或多個套件存有弱點，廠商表示將不會修補。說明
Linux/Unix 主機上安裝了一個或多個受到弱點影響的套件，且供應商未提供可用的修補程式。- 已解決 Linux 核心中的下列弱點：usb: gadget: f_fs: serialize DMABUF cancel against request completion ffs_epfile_dmabuf_io_complete() calls usb_ep_free_request() on the completed request but leaves priv->req, the back-pointer that ffs_dmabuf_transfer() set on submission, pointing at the freed memory. A later FUNCTIONFS_DMABUF_DETACH ioctl or ffs_epfile_release() on the close path still sees priv->req non-NULL under ffs->eps_lock: if (priv->ep && priv->req) usb_ep_dequeue(priv->ep, priv->req); so usb_ep_dequeue() is called on a freed usb_request. On dummy_hcd the dequeue path only walks a live queue and pointer-compares, so the freed pointer reads without faulting and KASAN requires an explicit check at the FunctionFS call site to surface the use-after-free. On SG-capable in-tree UDCs the dequeue path dereferences the supplied request immediately: * chipidea's ep_dequeue() does container_of(req, struct ci_hw_req, req) and reads hwreq->req.status before acquiring its own lock. * cdnsp's cdnsp_gadget_ep_dequeue() reads request->status first. The narrower option of clearing priv->req via cmpxchg() in the completion does not close the race: the completion runs without eps_lock, so a cancel path holding eps_lock can still observe priv->req non-NULL, race a concurrent completion that clears and frees, and pass the freed pointer to usb_ep_dequeue(). A slightly longer fix that moves the free into the cleanup work is needed. Same class of lifetime race as the recent usbip-vudc timer fix [1]. Take eps_lock in the sole place that mutates priv->req from the callback direction by moving usb_ep_free_request() out of the completion into ffs_dmabuf_cleanup(), the existing work handler scheduled by ffs_dmabuf_signal_done() on ffs->io_completion_wq. Clear priv->req there under eps_lock before freeing, and only clear if priv->req still names our request (a subsequent ffs_dmabuf_transfer() on the same attachment may have queued a new one). This keeps the existing dummy_hcd sync-dequeue invariant:
the completion callback is still invoked by the UDC without eps_lock held (dummy_hcd drops its own lock before calling the callback), and the callback now takes no f_fs lock at all. Serialization against the cancel path happens in cleanup, which runs from the workqueue with no f_fs lock held on entry. The priv ref count protects the containing ffs_dmabuf_priv: ffs_dmabuf_transfer() takes a ref via ffs_dmabuf_get(), cleanup drops it via ffs_dmabuf_put(), so priv stays live for the cleanup even after the cancel path's list_del + ffs_dmabuf_put. The ffs_dmabuf_transfer() error path no longer frees usb_req inline: fence->req and fence->ep are set before usb_ep_queue(), so ffs_dmabuf_cleanup() (scheduled by the error-path ffs_dmabuf_signal_done()) owns the free regardless of whether the queue succeeded. Reproduced under KASAN on both detach and close paths against dummy_hcd with an observability hook (kasan_check_byte(priv->req) immediately before usb_ep_dequeue) at the two FunctionFS cancel sites to surface the stale-pointer access;
the hook is not part of this patch. The KASAN allocator / free stacks in the captured splats identify the same request: alloc in dummy_alloc_request, free in dummy_timer, fault reached from ffs_epfile_release (close) and from the FUNCTIONFS_DMABUF_DETACH ioctl (detach). With the patch applied, both paths are silent under the same hook. The bug is reached from the FunctionFS device node, which in real deployments is owned by the privileged gadget daemon (adbd, UMS, composite gadget services, etc.); it is not reachable from unprivileged userspace or from a USB host on the cable. FunctionFS mounts default to GLOBAL_ROOT_UID, but the filesystem supports uid=, gid=, and fmode= delegation to a non-root gadget daemon, so on real deployments the attacker may be a less-privileged service rather than root. (CVE-2026-63894)
請注意，Nessus 依賴供應商報告的套件存在。
解決方案
目前尚未有已知的解決方案。另請參閱
Plugin 詳細資訊
嚴重性: High
ID: 328203
檔案名稱: unpatched_CVE_2026_63894.nasl
版本: 1.4
類型: Local
代理程式: unix
系列: Misc.
已發布: 2026/7/20
已更新: 2026/7/31
支援的感應器: Agentless Assessment, Frictionless Assessment Agent, Frictionless Assessment AWS, Frictionless Assessment Azure, Nessus Agent, Tenable Cloud Security, Tenable Self-Hosted Container Security, Nessus
風險資訊
VPR
風險因素: Medium
分數: 6.9
百分位數: 96.86
CVSS v2
風險因素: Medium
基本分數: 6.9
時間性分數: 5.9
媒介: CVSS2#AV:L/AC:M/Au:N/C:C/I:C/A:C
CVSS 評分資料來源: CVE-2026-63894
CVSS v3
風險因素: High
基本分數: 7.8
時間性分數: 7.1
媒介: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
時間媒介: CVSS:3.0/E:U/RL:U/RC:C
弱點資訊
CPE: cpe:/o:canonical:ubuntu_linux:16.04:-:lts, cpe:/o:canonical:ubuntu_linux:18.04:-:lts, cpe:/o:canonical:ubuntu_linux:20.04:-:lts, cpe:/o:canonical:ubuntu_linux:22.04:-:lts, cpe:/o:canonical:ubuntu_linux:24.04:-:lts, cpe:/o:canonical:ubuntu_linux:26.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:linux-allwinner-5.19, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.0, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.11, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.13, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.19, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.3, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.8, p-cpe:/a:canonical:ubuntu_linux:linux-aws-6.14, p-cpe:/a:canonical:ubuntu_linux:linux-aws-6.17, p-cpe:/a:canonical:ubuntu_linux:linux-aws-6.2, p-cpe:/a:canonical:ubuntu_linux:linux-aws-6.5, p-cpe:/a:canonical:ubuntu_linux:linux-azure-5.11, p-cpe:/a:canonical:ubuntu_linux:linux-azure-5.13, p-cpe:/a:canonical:ubuntu_linux:linux-azure-5.19, p-cpe:/a:canonical:ubuntu_linux:linux-azure-5.3, p-cpe:/a:canonical:ubuntu_linux:linux-azure-5.8, p-cpe:/a:canonical:ubuntu_linux:linux-azure-6.11, p-cpe:/a:canonical:ubuntu_linux:linux-azure-6.14, p-cpe:/a:canonical:ubuntu_linux:linux-azure-6.17, p-cpe:/a:canonical:ubuntu_linux:linux-azure-6.2, p-cpe:/a:canonical:ubuntu_linux:linux-azure-6.5, p-cpe:/a:canonical:ubuntu_linux:linux-azure-edge, p-cpe:/a:canonical:ubuntu_linux:linux-azure-fde-5.19, p-cpe:/a:canonical:ubuntu_linux:linux-azure-fde-6.14, p-cpe:/a:canonical:ubuntu_linux:linux-azure-fde-6.2, p-cpe:/a:canonical:ubuntu_linux:linux-azure-fde, p-cpe:/a:canonical:ubuntu_linux:linux-azure-nvidia-6.14, p-cpe:/a:canonical:ubuntu_linux:linux-azure, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-5.11, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-5.13, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-5.19, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-5.3, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-5.8, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-6.11, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-6.14, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-6.17, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-6.2, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-6.5, p-cpe:/a:canonical:ubuntu_linux:linux-gcp, p-cpe:/a:canonical:ubuntu_linux:linux-gke-4.15, p-cpe:/a:canonical:ubuntu_linux:linux-gke-5.15, p-cpe:/a:canonical:ubuntu_linux:linux-gke-5.4, p-cpe:/a:canonical:ubuntu_linux:linux-gke, p-cpe:/a:canonical:ubuntu_linux:linux-gkeop-5.15, p-cpe:/a:canonical:ubuntu_linux:linux-gkeop-5.4, p-cpe:/a:canonical:ubuntu_linux:linux-gkeop, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-5.11, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-5.13, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-5.19, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-5.8, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-6.11, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-6.14, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-6.17, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-6.2, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-6.5, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-edge, p-cpe:/a:canonical:ubuntu_linux:linux-hwe, p-cpe:/a:canonical:ubuntu_linux:linux-intel-5.13, p-cpe:/a:canonical:ubuntu_linux:linux-intel-iot-realtime, p-cpe:/a:canonical:ubuntu_linux:linux-lowlatency-hwe-5.19, p-cpe:/a:canonical:ubuntu_linux:linux-lowlatency-hwe-6.11, p-cpe:/a:canonical:ubuntu_linux:linux-lowlatency-hwe-6.2, p-cpe:/a:canonical:ubuntu_linux:linux-lowlatency-hwe-6.5, p-cpe:/a:canonical:ubuntu_linux:linux-nvidia-6.11, p-cpe:/a:canonical:ubuntu_linux:linux-nvidia-6.17, p-cpe:/a:canonical:ubuntu_linux:linux-nvidia-6.2, p-cpe:/a:canonical:ubuntu_linux:linux-nvidia-6.5, p-cpe:/a:canonical:ubuntu_linux:linux-nvidia-7.0, p-cpe:/a:canonical:ubuntu_linux:linux-nvidia-bos, p-cpe:/a:canonical:ubuntu_linux:linux-nvidia, p-cpe:/a:canonical:ubuntu_linux:linux-oem-5.10, p-cpe:/a:canonical:ubuntu_linux:linux-oem-5.13, p-cpe:/a:canonical:ubuntu_linux:linux-oem-5.14, p-cpe:/a:canonical:ubuntu_linux:linux-oem-5.17, p-cpe:/a:canonical:ubuntu_linux:linux-oem-5.6, p-cpe:/a:canonical:ubuntu_linux:linux-oem-6.0, p-cpe:/a:canonical:ubuntu_linux:linux-oem-6.11, p-cpe:/a:canonical:ubuntu_linux:linux-oem-6.14, p-cpe:/a:canonical:ubuntu_linux:linux-oem-6.17, p-cpe:/a:canonical:ubuntu_linux:linux-oem-6.1, p-cpe:/a:canonical:ubuntu_linux:linux-oem-6.5, p-cpe:/a:canonical:ubuntu_linux:linux-oem-6.8, p-cpe:/a:canonical:ubuntu_linux:linux-oem, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-5.0, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-5.11, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-5.13, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-5.3, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-5.8, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-6.14, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-6.17, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-6.5, p-cpe:/a:canonical:ubuntu_linux:linux-raspi-realtime, p-cpe:/a:canonical:ubuntu_linux:linux-raspi2, p-cpe:/a:canonical:ubuntu_linux:linux-realtime, p-cpe:/a:canonical:ubuntu_linux:linux-riscv-5.11, p-cpe:/a:canonical:ubuntu_linux:linux-riscv-5.19, p-cpe:/a:canonical:ubuntu_linux:linux-riscv-5.8, p-cpe:/a:canonical:ubuntu_linux:linux-riscv-6.14, p-cpe:/a:canonical:ubuntu_linux:linux-riscv-6.17, p-cpe:/a:canonical:ubuntu_linux:linux-riscv-6.5, p-cpe:/a:canonical:ubuntu_linux:linux-riscv, p-cpe:/a:canonical:ubuntu_linux:linux-starfive-5.19, p-cpe:/a:canonical:ubuntu_linux:linux-starfive-6.2, p-cpe:/a:canonical:ubuntu_linux:linux-starfive-6.5
必要的 KB 項目: Host/cpu, Host/local_checks_enabled, global_settings/vendor_unpatched, Host/OS/identifier
可輕鬆利用: No known exploits are available
弱點發布日期: 2026/7/19
參考資訊
CVE: CVE-2026-63894