CVE-2026-90291

Summary

In the Linux kernel, the following vulnerability has been resolved:

module/dups: Fix use-after-free in kmod_dup_req lifetime handling

The kmod dups code uses RCU to ensure that a kmod_dup_req instance is freed only after it is no longer referenced. When releasing an instance, the kmod_dup_request_delete() function removes the kmod_dup_req from the dup_kmod_reqs list, waits via synchronize_rcu() and finally frees it. However, this doesn't work correctly because parallel users referencing the instance in kmod_dup_request_exists_wait() don't enter an RCU read-side critical section. This can result in a use-after-free.

The kmod_dup_request_exists_wait() function may need to hold a valid reference to a kmod_dup_req instance across a blocking wait until the corresponding modprobe command completes. This makes it unsuitable for RCU.

Fix the issue by changing the lifecycle management of kmod_dup_req to use reference counting.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/2c85e0fb528e039aa8ea1e9c2a1f64347f990541
• https://git.kernel.org/stable/c/b2709aad7599f6fd957939b60f4a8323c8f08072
• https://git.kernel.org/stable/c/cd2396fc9684d2cfd3f3c3f09c79d6d9d725b0ca
• https://git.kernel.org/stable/c/5eecb11b543f9f417bcf0dea239ff99c6af65dbd

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