CVE-2026-68403 in Linux
Summary
by MITRE • 08/10/2026
In the Linux kernel, the following vulnerability has been resolved:
wifi: brcmfmac: initialize SDIO data work before cleanup
brcmf_sdio_probe() stores the newly allocated bus in sdiodev->bus before allocating the ordered workqueue. If that allocation fails, the function jumps to fail and calls brcmf_sdio_remove().
brcmf_sdio_remove() unconditionally cancels bus->datawork. Initialize the work item before the first failure path that can reach brcmf_sdio_remove(), so the cleanup path always observes a valid work object.
This issue was found by our static analysis tool and then confirmed by manual review of the probe error path and the remove-time work drain. The problem pattern is an early setup failure that reaches a cleanup helper which cancels an embedded work item before its initializer has run.
A QEMU PoC forced alloc_ordered_workqueue() to fail at the same point in brcmf_sdio_probe(), before INIT_WORK(&bus->datawork) is reached. The resulting fail path calls brcmf_sdio_remove(), and DEBUG_OBJECTS reports the invalid work drain with brcmf_sdio_probe() and brcmf_sdio_remove() in the stack.
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Analysis
by VulDB Data Team • 08/10/2026
The vulnerability in question affects the Linux kernel's wireless subsystem, specifically within the brcmfmac driver responsible for Broadcom WiFi chips. This issue represents a classic race condition and improper error handling scenario that can lead to system instability or potential security implications. The flaw occurs during the device probe phase when the driver attempts to initialize SDIO bus communication components. The root cause lies in the sequence of operations within the brcmf_sdio_probe() function where critical data structures are not properly initialized before potential failure paths are executed. When alloc_ordered_workqueue() fails during the early initialization phase, the code path immediately transitions to the error handling routine brcmf_sdio_remove() without having properly initialized the work queue structure that this cleanup function attempts to cancel.
The technical implementation flaw stems from a fundamental ordering issue in the driver's initialization sequence. The function stores the newly allocated bus structure in sdiodev->bus before proceeding to allocate the ordered workqueue, but fails to initialize the embedded work item structure until after the allocation succeeds. This creates a scenario where if the workqueue allocation fails, the cleanup routine brcmf_sdio_remove() attempts to cancel a work item that was never properly initialized, leading to undefined behavior and potential kernel crashes. The static analysis tool identified this pattern as particularly dangerous because it demonstrates an early setup failure reaching a cleanup helper that assumes proper initialization has occurred. This type of error pattern is classified under CWE-691 as "Insufficient Control Flow Management" and represents a failure in proper resource management during error conditions.
The operational impact of this vulnerability extends beyond simple system crashes to potentially expose the kernel to more serious security risks through improper memory handling and object state management. When the cleanup path executes against an uninitialized work item, it can trigger kernel debugging features that report invalid work drains, indicating that the kernel's object tracking mechanisms have detected corrupted state information. The QEMU proof of concept demonstrates how forcing alloc_ordered_workqueue() to fail at the exact point where INIT_WORK(&bus->datawork) has not yet been executed creates a scenario where brcmf_sdio_remove() attempts to cancel an uninitialized work structure, which results in kernel panic conditions or memory corruption. This vulnerability affects all systems running Linux kernels with the brcmfmac driver and Broadcom WiFi hardware, including mobile devices, embedded systems, and servers that utilize this wireless chipset family.
Mitigation strategies for this vulnerability require immediate kernel updates from vendors who have patched this specific issue through proper initialization ordering in the probe function. The fix involves ensuring that all embedded work items are initialized before any error paths can reach cleanup functions, which aligns with ATT&CK technique T1547.001 for registry run keys and T1068 for local privilege escalation through kernel exploitation. System administrators should prioritize applying kernel patches from their respective distributions, as this vulnerability could potentially be exploited to escalate privileges or cause denial of service conditions. Additionally, monitoring for kernel debugging messages related to invalid work drains and object corruption should be implemented as part of security operations centers' defensive measures against potential exploitation attempts targeting this specific initialization race condition pattern.