CVE-2022-50709 in Linux
Summary
by MITRE • 12/24/2025
In the Linux kernel, the following vulnerability has been resolved:
wifi: ath9k: avoid uninit memory read in ath9k_htc_rx_msg()
syzbot is reporting uninit value at ath9k_htc_rx_msg() [1], for
ioctl(USB_RAW_IOCTL_EP_WRITE) can call ath9k_hif_usb_rx_stream() with pkt_len = 0 but ath9k_hif_usb_rx_stream() uses __dev_alloc_skb(pkt_len + 32, GFP_ATOMIC) based on an assumption that pkt_len is valid. As a result, ath9k_hif_usb_rx_stream() allocates skb with uninitialized memory and ath9k_htc_rx_msg() is reading from uninitialized memory.
Since bytes accessed by ath9k_htc_rx_msg() is not known until ath9k_htc_rx_msg() is called, it would be difficult to check minimal valid pkt_len at "if (pkt_len > 2 * MAX_RX_BUF_SIZE) {" line in
ath9k_hif_usb_rx_stream().
We have two choices. One is to workaround by adding __GFP_ZERO so that ath9k_htc_rx_msg() sees 0 if pkt_len is invalid. The other is to let ath9k_htc_rx_msg() validate pkt_len before accessing. This patch chose the latter.
Note that I'm not sure threshold condition is correct, for I can't find details on possible packet length used by this protocol.
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Analysis
by VulDB Data Team • 02/24/2026
The vulnerability described in CVE-2022-50709 resides within the Linux kernel's wireless networking subsystem, specifically in the ath9k driver implementation for Atheros wireless hardware. This issue manifests as an uninitialized memory read condition that occurs during USB communication handling, representing a classic security flaw that can potentially lead to information disclosure or system instability. The vulnerability was identified through automated fuzzing mechanisms, with syzbot reporting the specific memory access pattern that triggers the problematic code path. The flaw exists in the interaction between USB raw ioctl operations and the wireless driver's receive message processing functions, creating a scenario where invalid packet length parameters can cause memory corruption.
The technical root cause stems from a fundamental assumption violation within the ath9k_hif_usb_rx_stream() function which allocates network buffers using __dev_alloc_skb() based on a packet length parameter that may legitimately be zero. When ioctl(USB_RAW_IOCTL_EP_WRITE) is invoked with pkt_len = 0, the allocation proceeds but creates an skb buffer containing uninitialized memory. Subsequently, the ath9k_htc_rx_msg() function attempts to read from this uninitialized memory without proper validation, creating a potential attack surface where malicious actors could potentially extract sensitive kernel memory contents. This pattern aligns with CWE-457: Use of Uninitialized Variable, and represents a memory safety issue that can be classified under the ATT&CK technique T1005: Data from Local System. The vulnerability demonstrates poor input validation and memory management practices where the code assumes valid parameters without proper bounds checking.
The operational impact of this vulnerability extends beyond simple information disclosure, as uninitialized memory reads can potentially lead to more severe consequences including privilege escalation or denial of service attacks. Attackers could exploit this condition by crafting specific USB raw ioctl commands that trigger the zero-length packet scenario, causing the kernel to read from uninitialized memory locations. This creates a risk of exposing kernel memory contents including cryptographic keys, credentials, or other sensitive data that may be present in the uninitialized buffer regions. The vulnerability affects systems running Linux kernels with the ath9k wireless driver and USB-based wireless hardware, particularly those implementing USB raw ioctl functionality for wireless communication. The memory access pattern is difficult to predict and validate because the exact packet length requirements for the specific wireless protocol are not well-documented, making it challenging to establish proper bounds checking without potentially breaking legitimate functionality.
The patch addressing this vulnerability implements a defensive programming approach by adding explicit validation of the packet length parameter before any memory access operations occur within ath9k_htc_rx_msg(). This mitigation strategy aligns with the principle of least privilege and defensive programming practices recommended in secure coding standards. The solution avoids the potential complexity of memory zeroing approaches by ensuring that invalid packet lengths are rejected at the input validation stage rather than attempting to mask the problem through memory initialization. This approach follows the ATT&CK technique T1082: System Information Discovery, as it addresses potential information leakage through memory access patterns, and represents a proper security fix that prevents the propagation of invalid data through the kernel's wireless subsystem. The fix ensures that the wireless driver properly validates input parameters before processing, reducing the attack surface and preventing potential exploitation through uninitialized memory reads.