Linux Kernel ath5k Driver Array Index Out-of-Bounds Vulnerability

A vulnerability in the ath5k wireless driver of the Linux kernel has been identified, where the driver improperly accesses an array, leading to an array-index-out-of-bounds condition. This issue was highlighted by a Undefined Behavior Sanitizer (UBSAN) message indicating that an index was out of range for the expected data type. The problem arises because the driver does not correctly validate array indices before use, which can potentially lead to memory corruption, although in this case, the out-of-bounds write only overwrites a nearby variable related to acknowledgment signals.

Impact

Exploitation of this vulnerability could lead to memory corruption by overwriting adjacent data in the structure that holds transmission status information. While the specific impact on the system's operation may be minimal, such memory corruption issues can sometimes be leveraged for more severe consequences, such as arbitrary code execution or causing a system crash.

Reproduction

The vulnerability can be reproduced by triggering a condition where the 'ts_final_idx' variable in the transmission status structure is set to 3. This can be done by simulating a scenario where the ath5k driver processes a transmission status update that exceeds the valid range of the 'ieee80211_tx_rate' array, which is defined to hold a maximum of 4 rates. When this happens, the driver attempts to access an index that is out of bounds, leading to the reported array-index-out-of-bounds error.

Remediation

The vulnerability has been addressed in the Linux kernel. Users should upgrade to the latest version of the stable Linux kernel where this issue has been fixed.