CVE-2026-74331 firmware_loader: Fix recursive lock in device_cache_fw_images()
A recursive locking deadlock in the Linux kernel firmware loader can cause a system hang during suspend or hibernation when memory allocation fails.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-74331?
CVE-2026-74331 is a denial of service vulnerability in Linux, published on 15 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
firmware_loader: Fix recursive lock in device_cache_fw_images()
A recursive locking deadlock can occur in the firmware loader's power management notification handler.
During system suspend or hibernation preparation, fw_pm_notify() calls device_cache_fw_images(). This function acquires fw_lock to set the firmware cache state to FW_LOADER_START_CACHE and then iterates over all devices using dpm_for_each_dev() while still holding the lock.
For each device, dev_cache_fw_image() schedules asynchronous work to cache the firmware. If memory allocation for the async work entry fails (e.g., in out-of-memory conditions), async_schedule_node_domain() falls back to executing the work function synchronously in the current thread.
The synchronous execution path (__async_dev_cache_fw_image() -> cache_firmware() -> request_firmware() -> assign_fw()) attempts to acquire fw_lock again. Since the current thread already holds fw_lock, this results in a recursive locking deadlock.
Fix this by releasing fw_lock immediately after updating the cache state and before calling dpm_for_each_dev(). The lock is only needed to protect the state update. Concurrent firmware requests will correctly see the FW_LOADER_START_CACHE state and use the piggyback mechanism, which is independently protected by its own fwc->name_lock.
Which versions are affected by CVE-2026-74331?
How do I fix CVE-2026-74331?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-74331 being exploited?
There is no known exploitation of CVE-2026-74331 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-74331, DEBIAN-CVE-2026-74331, GHSA-2whr-3329-9322, UBUNTU-CVE-2026-74331.