CVE-2022-49755: linux kernel Use-After-Free — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_fs: Prevent race during ffs_ep0_queue_wait While performing fast composition switch, there is a possibility that the process of ffs_ep0_write/ffs_ep0_read get into a race condition due to ep0req being freed up from functionfs_unbind. Consider the scenario that the ffs_ep0_write calls the ffs_ep0_queue_wait by taking a lock &ffs->ev.waitq.lock. However, the functionfs_unbind isn't bounded so it can go ahead and mark the ep0req to NULL, and since there is no NULL check in ffs_ep0_queue_wait we will end up in use-after-free. Fix this by making a serialized execution between the two functions using a mutex_lock(ffs->mutex).

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CVSS v3.1 Score

7.8

HIGH

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Weakness Type (CWE)

CWE-416 Use After Free

Affected Products

Vendor	Product	Versions
linux	linux_kernel	2.6.35 — 4.14.305
linux	linux_kernel	4.15 — 4.19.272
linux	linux_kernel	4.20 — 5.4.231
linux	linux_kernel	5.5 — 5.10.166
linux	linux_kernel	5.11 — 5.15.91
linux	linux_kernel	5.16 — 6.1.9
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All

References

Advisories & Patches

https://git.kernel.org/stable/c/6a19da111057f69214b97c62fb0ac59023970850 https://git.kernel.org/stable/c/6aee197b7fbcd61596a78b47d553f2f99111f217 https://git.kernel.org/stable/c/6dd9ea05534f323668db94fcc2726c7a84547e78 https://git.kernel.org/stable/c/a8d40942df074f4ebcb9bd3413596d92f323b064 https://git.kernel.org/stable/c/ae8e136bcaae96163b5821984de1036efc9abb1a https://git.kernel.org/stable/c/e9036e951f93fb8d7b5e9d6e2c7f94a4da312ae4 https://git.kernel.org/stable/c/facf353c9e8d7885b686d9a4b173d4e0af6441d2

Frequently Asked Questions

What is CVE-2022-49755? +

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_fs: Prevent race during ffs_ep0_queue_wait While performing fast composition switch, there is a possibility that the process of ffs_ep0_write/ffs_ep0_read get into a race condition due to ep0req being freed up from functionfs_unbind. Consider the scenario that the ffs_ep0_write calls the ffs_ep0_queue_wait by taking a lock &ffs->ev.waitq.lock. However, the functionfs_unbind isn't bounded so it can go ahead and mark the ep0req to NULL, and since there is no NULL check in ffs_ep0_queue_wait we will end up in use-after-free. Fix this by making a serialized execution between the two functions using a mutex_lock(ffs->mutex). It has a CVSS v3.1 base score of 7.8 (HIGH).

How severe is CVE-2022-49755? +

CVE-2022-49755 has a CVSS v3.1 score of 7.8 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

What products are affected by CVE-2022-49755? +

CVE-2022-49755 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2022-49755? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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