soc：qcom：pmic_glink_altmode：修复 drm 桥释放后使用 (CVE-2024-26909)

CVE编号

CVE-2024-26909

利用情况

暂无

补丁情况

N/A

披露时间

2024-04-17
漏洞描述
In the Linux kernel, the following vulnerability has been resolved:

soc: qcom: pmic_glink_altmode: fix drm bridge use-after-free

A recent DRM series purporting to simplify support for "transparent
bridges" and handling of probe deferrals ironically exposed a
use-after-free issue on pmic_glink_altmode probe deferral.

This has manifested itself as the display subsystem occasionally failing
to initialise and NULL-pointer dereferences during boot of machines like
the Lenovo ThinkPad X13s.

Specifically, the dp-hpd bridge is currently registered before all
resources have been acquired which means that it can also be
deregistered on probe deferrals.

In the meantime there is a race window where the new aux bridge driver
(or PHY driver previously) may have looked up the dp-hpd bridge and
stored a (non-reference-counted) pointer to the bridge which is about to
be deallocated.

When the display controller is later initialised, this triggers a
use-after-free when attaching the bridges:

dp -> aux -> dp-hpd (freed)

which may, for example, result in the freed bridge failing to attach:

[drm:drm_bridge_attach [drm]] *ERROR* failed to attach bridge /soc@0/phy@88eb000 to encoder TMDS-31: -16

or a NULL-pointer dereference:

Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
...
Call trace:
drm_bridge_attach+0x70/0x1a8 [drm]
drm_aux_bridge_attach+0x24/0x38 [aux_bridge]
drm_bridge_attach+0x80/0x1a8 [drm]
dp_bridge_init+0xa8/0x15c [msm]
msm_dp_modeset_init+0x28/0xc4 [msm]

The DRM bridge implementation is clearly fragile and implicitly built on
the assumption that bridges may never go away. In this case, the fix is
to move the bridge registration in the pmic_glink_altmode driver to
after all resources have been looked up.

Incidentally, with the new dp-hpd bridge implementation, which registers
child devices, this is also a requirement due to a long-standing issue
in driver core that can otherwise lead to a probe deferral loop (see
commit fbc35b45f9f6 ("Add documentation on meaning of -EPROBE_DEFER")).

[DB: slightly fixed commit message by adding the word 'commit']
解决建议
建议您更新当前系统或软件至最新版，完成漏洞的修复。
参考链接
https://git.kernel.org/stable/c/2bbd65c6ca567ed8dbbfc4fb945f57ce64bef342
https://git.kernel.org/stable/c/b979f2d50a099f3402418d7ff5f26c3952fb08bb
https://git.kernel.org/stable/c/ef45aa2841e15b649e5417fe3d4de395fe462781
受影响软件情况
# 类型 厂商 产品 版本 影响面
1
运行在以下环境
系统 debian_10 linux * Up to
(excluding)
4.19.304-1
运行在以下环境
系统 debian_11 linux * Up to
(excluding)
5.10.209-2
运行在以下环境
系统 debian_12 linux * Up to
(excluding)
6.1.85-1
运行在以下环境
系统 linux linux_kernel * From
(including)
6.3 		Up to
(excluding)
6.6.23
运行在以下环境
系统 linux linux_kernel * From
(including)
6.7 		Up to
(excluding)
6.7.11
CVSS3评分
5.5
  • 攻击路径
    本地
  • 攻击复杂度
    低
  • 权限要求
    低
  • 影响范围
    未更改
  • 用户交互
    无
  • 可用性
    高
  • 保密性
    无
  • 完整性
    无
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CWE-ID 漏洞类型
CWE-416 释放后使用
阿里云安全产品覆盖情况