Bug 2425119 (CVE-2022-50740)

Summary: CVE-2022-50740 kernel: Linux kernel: Denial of Service in ath9k Wi-Fi driver due to URB memory leak
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: medium    
Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in the Linux kernel's ath9k Wi-Fi driver. This memory leak vulnerability occurs because Universal Serial Bus (USB) request blocks (URBs) are allocated but not properly freed when certain conditions are met during USB device handling. A local attacker could exploit this by triggering the specific USB device handling, leading to a denial of service due to resource exhaustion.
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Description OSIDB Bzimport 2025-12-24 14:04:16 UTC 
In the Linux kernel, the following vulnerability has been resolved:

wifi: ath9k: hif_usb: fix memory leak of urbs in ath9k_hif_usb_dealloc_tx_urbs()

Syzkaller reports a long-known leak of urbs in
ath9k_hif_usb_dealloc_tx_urbs().

The cause of the leak is that usb_get_urb() is called but usb_free_urb()
(or usb_put_urb()) is not called inside usb_kill_urb() as urb->dev or
urb->ep fields have not been initialized and usb_kill_urb() returns
immediately.

The patch removes trying to kill urbs located in hif_dev->tx.tx_buf
because hif_dev->tx.tx_buf is not supposed to contain urbs which are in
pending state (the pending urbs are stored in hif_dev->tx.tx_pending).
The tx.tx_lock is acquired so there should not be any changes in the list.

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
Comment 1 Alexander B 2025-12-25 01:08:29 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025122448-CVE-2022-50740-a780@gregkh/T