CVE-2023-53641: linux kernel — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: wifi: ath9k: hif_usb: fix memory leak of remain_skbs hif_dev->remain_skb is allocated and used exclusively in ath9k_hif_usb_rx_stream(). It is implied that an allocated remain_skb is processed and subsequently freed (in error paths) only during the next call of ath9k_hif_usb_rx_stream(). So, if the urbs are deallocated between those two calls due to the device deinitialization or suspend, it is possible that ath9k_hif_usb_rx_stream() is not called next time and the allocated remain_skb is leaked. Our local Syzkaller instance was able to trigger that. remain_skb makes sense when receiving two consecutive urbs which are logically linked together, i.e. a specific data field from the first skb indicates a cached skb to be allocated, memcpy'd with some data and subsequently processed in the next call to ath9k_hif_usb_rx_stream(). Urbs deallocation supposedly makes that link irrelevant so we need to free the cached skb in those cases. Fix the leak by introducing a function to explicitly free remain_skb (if it is not NULL) when the rx urbs have been deallocated. remain_skb is NULL when it has not been allocated at all (hif_dev struct is kzalloced) or when it has been processed in next call to ath9k_hif_usb_rx_stream(). Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

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CVSS v3.1 Score

5.5

MEDIUM

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

Weakness Type (CWE)

CWE-401 CWE-401

Affected Products

Vendor	Product	Versions
linux	linux_kernel	2.6.35 — 4.19.283
linux	linux_kernel	4.20 — 5.4.243
linux	linux_kernel	5.5 — 5.10.180
linux	linux_kernel	5.11 — 5.15.111
linux	linux_kernel	5.16 — 6.1.28
linux	linux_kernel	6.2 — 6.2.15
linux	linux_kernel	6.3 — 6.3.2

References

Advisories & Patches

https://git.kernel.org/stable/c/320d760a35273aa815d58b57e4fd9ba5279a3489 https://git.kernel.org/stable/c/59073060fe0950c6ecbe12bdc06469dcac62128d https://git.kernel.org/stable/c/6719e3797ec52cd144c8a5ba8aaab36674800585 https://git.kernel.org/stable/c/7654cc03eb699297130b693ec34e25f77b17c947 https://git.kernel.org/stable/c/8f02d538878c9b1501f624595eb22ee4e5e0ff84 https://git.kernel.org/stable/c/9b9356a3014123f0ce4b50d9278c1265173150ab https://git.kernel.org/stable/c/d9899318660791141ea6002fda5577b2c5d7386e https://git.kernel.org/stable/c/f0931fc8f4b6847c72e170d2326861c0a081d680

Frequently Asked Questions

What is CVE-2023-53641? +

In the Linux kernel, the following vulnerability has been resolved: wifi: ath9k: hif_usb: fix memory leak of remain_skbs hif_dev->remain_skb is allocated and used exclusively in ath9k_hif_usb_rx_stream(). It is implied that an allocated remain_skb is processed and subsequently freed (in error paths) only during the next call of ath9k_hif_usb_rx_stream(). So, if the urbs are deallocated between those two calls due to the device deinitialization or suspend, it is possible that ath9k_hif_usb_rx_stream() is not called next time and the allocated remain_skb is leaked. Our local Syzkaller instance was able to trigger that. remain_skb makes sense when receiving two consecutive urbs which are logically linked together, i.e. a specific data field from the first skb indicates a cached skb to be allocated, memcpy'd with some data and subsequently processed in the next call to ath9k_hif_usb_rx_stream(). Urbs deallocation supposedly makes that link irrelevant so we need to free the cached skb in those cases. Fix the leak by introducing a function to explicitly free remain_skb (if it is not NULL) when the rx urbs have been deallocated. remain_skb is NULL when it has not been allocated at all (hif_dev struct is kzalloced) or when it has been processed in next call to ath9k_hif_usb_rx_stream(). Found by Linux Verification Center (linuxtesting.org) with Syzkaller. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2023-53641? +

CVE-2023-53641 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2023-53641? +

CVE-2023-53641 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-2023-53641? +

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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CVE-2023-53641