Buffer Overflow in Linux Kernel WiFi Driver

Executive Summary

This vulnerability in the Linux kernel involves improper validation of monitor transmit frame lengths in the rtl8723bs driver. The function rtw_cfg80211_monitor_if_xmit_entry removes the radiotap header but fails to check if a base 802.11 header remains. It also reads header spans before confirming the skb contains sufficient data, leading to potential out-of-bounds reads or insufficient data for Ethernet address writes.

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Detection Guidance

This vulnerability affects the Linux kernel's staging driver for RTL8723BS Wi-Fi chips. Detection requires checking if your system uses this driver and kernel version. Inspect loaded kernel modules with lsmod | grep rtl8723bs. Verify kernel version with uname -r. If the driver is loaded and kernel is vulnerable, monitor for crashes or memory corruption during Wi-Fi operations.

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Impact Analysis

This vulnerability could allow an attacker to cause memory corruption or crashes by sending malformed network frames. It may lead to denial-of-service conditions or potential privilege escalation if exploited. Systems using vulnerable Linux kernels with the rtl8723bs driver are at risk.

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Mitigation Strategies

Update your Linux kernel to the latest stable version where this issue is patched. If using a custom or vendor kernel, check for backported fixes. Temporarily unload the rtl8723bs module with rmmod rtl8723bs if not actively used. Disable Wi-Fi interfaces using this driver until patched.

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