CVE-2023-53641: wifi: ath9k: hif_usb: fix memory leak of remain_skbs

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-10-07 · updated 2026-06-17
Weakness: CWE-401

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.

Affected products

Linux kernel: from 2.6.35 before 4.19.283; from 4.20 before 5.4.243; from 5.5 before 5.10.180; from 5.11 before 5.15.111; from 5.16 before 6.1.28; from 6.2 before 6.2.15 — fixed in 4.19.283, 5.10.180, 5.15.111, 5.4.243, 6.1.28, 6.2.15

How to fix

Upgrade to a fixed version: Linux kernel 4.19.283, 5.10.180, 5.15.111, 5.4.243. Check the vendor advisory for mitigations.

References

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