gpiolib:cdev:修复 lineinfo_changed_notify 中释放后使用的问题(CVE-2024-36899)

CVE编号

CVE-2024-36899

利用情况

暂无

补丁情况

N/A

披露时间

2024-05-31
漏洞描述
In the Linux kernel, the following vulnerability has been resolved:

gpiolib: cdev: Fix use after free in lineinfo_changed_notify

The use-after-free issue occurs as follows: when the GPIO chip device file
is being closed by invoking gpio_chrdev_release(), watched_lines is freed
by bitmap_free(), but the unregistration of lineinfo_changed_nb notifier
chain failed due to waiting write rwsem. Additionally, one of the GPIO
chip's lines is also in the release process and holds the notifier chain's
read rwsem. Consequently, a race condition leads to the use-after-free of
watched_lines.

Here is the typical stack when issue happened:

[free]
gpio_chrdev_release()
--> bitmap_free(cdev->watched_lines) <-- freed
--> blocking_notifier_chain_unregister()
--> down_write(&nh->rwsem) <-- waiting rwsem
--> __down_write_common()
--> rwsem_down_write_slowpath()
--> schedule_preempt_disabled()
--> schedule()

[use]
st54spi_gpio_dev_release()
--> gpio_free()
--> gpiod_free()
--> gpiod_free_commit()
--> gpiod_line_state_notify()
--> blocking_notifier_call_chain()
--> down_read(&nh->rwsem); <-- held rwsem
--> notifier_call_chain()
--> lineinfo_changed_notify()
--> test_bit(xxxx, cdev->watched_lines) <-- use after free

The side effect of the use-after-free issue is that a GPIO line event is
being generated for userspace where it shouldn't. However, since the chrdev
is being closed, userspace won't have the chance to read that event anyway.

To fix the issue, call the bitmap_free() function after the unregistration
of lineinfo_changed_nb notifier chain.
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。
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
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