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The vulnerability CVE-2025-38643 in the Linux kernel arises from a missing mutex lock in the WiFi cfg80211 subsystem. Specifically, the worker function cfg80211_propagate_cac_done_wk() is responsible for propagating Channel Availability Check (CAC) completion in WiFi networks. This function calls wdev_chandef() to retrieve wireless device channel definitions. However, callers of wdev_chandef() must hold the wiphy mutex to ensure thread safety and prevent race conditions. The worker cfg80211_propagate_cac_done_wk() fails to acquire this mutex before invoking wdev_chandef(). This omission triggers a kernel warning when the mesh_peer_connected_dfs test from hostapd is executed with certain mac80211 code changes. The warning indicates a potential race condition where concurrent access to channel data could lead to inconsistent state or corruption. This issue is particularly relevant in mesh networking scenarios using Dynamic Frequency Selection (DFS) channels. The missing lock might allow other threads to modify channel configurations simultaneously, causing undefined behavior, system instability, or crashes. Although the immediate effect is a warning log, it could escalate under heavy load or specific network conditions. The vulnerability was resolved by adding the required wiphy mutex lock in the worker function to comply with locking protocols.
Platform: Linux Kernel
Version: 6.14.0-rc5
Vulnerability: Missing Lock Warning
Severity: Medium
date: 2025-08-22
Prediction: Patched 2025-08-22
What Undercode Say:
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Check kernel warnings:
dmesg | grep "WARNING"
Monitor WiFi module logs:
journalctl -k | grep cfg80211
Code snippet from vulnerable area:
// In cfg80211_propagate_cac_done_wk() // Missing wiphy_lock() before wdev_chandef() struct wireless_dev wdev; struct cfg80211_chan_def chandef = wdev_chandef(wdev);
How Exploit:
Trigger mesh DFS tests.
Cause kernel warning floods.
Potential race condition exploitation.
Protection from this CVE
Update Linux kernel.
Apply patch mutex.
Disable vulnerable features.
Impact:
Kernel warning triggers.
Possible system instability.
WiFi mesh disruptions.
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Sources:
Reported By: nvd.nist.gov
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