CVE-2026-31726

Katalog CVE

CVSS 5.5 · Medium EPSS 0,16%

Kerentanan NULL Pointer Dereference pada linux kernel. Skor CVSS 3.1 5.5 (Medium) menurut NVD.

Deskripsi (NVD)

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: uvc: fix NULL pointer dereference during unbind race Commit b81ac4395bbe ("usb: gadget: uvc: allow for application to cleanly shutdown") introduced two stages of synchronization waits totaling 1500ms in uvc_function_unbind() to prevent several types of kernel panics. However, this timing-based approach is insufficient during power management (PM) transitions. When the PM subsystem starts freezing user space processes, the wait_event_interruptible_timeout() is aborted early, which allows the unbind thread to proceed and nullify the gadget pointer (cdev->gadget = NULL): [ 814.123447][ T947] configfs-gadget.g1 gadget.0: uvc: uvc_function_unbind() [ 814.178583][ T3173] PM: suspend entry (deep) [ 814.192487][ T3173] Freezing user space processes [ 814.197668][ T947] configfs-gadget.g1 gadget.0: uvc: uvc_function_unbind no clean disconnect, wait for release When the PM subsystem resumes or aborts the suspend and tasks are restarted, the V4L2 release path is executed and attempts to access the already nullified gadget pointer, triggering a kernel panic: [ 814.292597][ C0] PM: pm_system_irq_wakeup: 479 triggered dhdpcie_host_wake [ 814.386727][ T3173] Restarting tasks ... [ 814.403522][ T4558] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000030 [ 814.404021][ T4558] pc : usb_gadget_deactivate+0x14/0xf4 [ 814.404031][ T4558] lr : usb_function_deactivate+0x54/0x94 [ 814.404078][ T4558] Call trace: [ 814.404080][ T4558] usb_gadget_deactivate+0x14/0xf4 [ 814.404083][ T4558] usb_function_deactivate+0x54/0x94 [ 814.404087][ T4558] uvc_function_disconnect+0x1c/0x5c [ 814.404092][ T4558] uvc_v4l2_release+0x44/0xac [ 814.404095][ T4558] v4l2_release+0xcc/0x130 Address the race condition and NULL pointer dereference by: 1. State Synchronization (flag + mutex) Introduce a 'func_unbound' flag in struct uvc_device. This allows uvc_function_disconnect() to safely skip accessing the nullified cdev->gadget pointer. As suggested by Alan Stern, this flag is protected by a new mutex (uvc->lock) to ensure proper memory ordering and prevent instruction reordering or speculative loads. This mutex is also used to protect 'func_connected' for consistent state management. 2. Explicit Synchronization (completion) Use a completion to synchronize uvc_function_unbind() with the uvc_vdev_release() callback. This prevents Use-After-Free (UAF) by ensuring struct uvc_device is freed after all video device resources are released.

Rincian

Terbit di NVD

1 Mei 2026

Terakhir diubah

17 Juni 2026

Status NVD

Analyzed

CVSS 3.1

5.5 (Medium), sumber NVD
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H · uraikan di kalkulator

Jenis kelemahan (CWE)

CWE-476: NULL Pointer Dereference

EPSS (30 hari)

0,16% peluang dieksploitasi; lebih tinggi dari 4,4% CVE lain

Produk dan versi terdampak

> Data dari konfigurasi CPE di NVD.

Referensi dan perbaikan

• https://git.kernel.org/stable/c/0587de744615628c38e33ddc1601160a5ea8c50a patch
• https://git.kernel.org/stable/c/0c00ec409d7b2bce3fcac73188b79a141db7cfda patch
• https://git.kernel.org/stable/c/1aa9356881ee4ed414bf72d0c56d915492cb5345 patch
• https://git.kernel.org/stable/c/8a1128d604c360eca135f15b882b70256a522145 patch
• https://git.kernel.org/stable/c/c038ba56b92e410d1caec22b2dc68780a0b42091 patch
• https://git.kernel.org/stable/c/c78e463ee134b4669579d453c81ae00795e4c19a patch
• https://git.kernel.org/stable/c/d92d1532e05b1b31d36d48765e43bf73d793d19f patch
• https://git.kernel.org/stable/c/eba2936bbe6b752a31725a9eb5c674ecbf21ee7d patch