CVE-2022-48985
CriticalCVSS 9.8Exploitation Probability (EPSS)
Low risk45th percentile - higher than 45% of all known CVEs
Summary
In the Linux kernel, the mana network driver has a race condition on the per-CQ variable napi work_done. After calling napi_complete_done(), the NAPIF_STATE_SCHED bit may be cleared, and another CPU can start the napi thread and access the per-CQ variable cq->work_done. If another thread sets it to a value >= budget, this thread will continue to run when it should stop, potentially causing memory corruption and panic. The fix saves the work_done variable in a local variable before napi_complete_done() to avoid corruption.
Risk Assessment
The vulnerability could lead to memory corruption and system crash, and may also prevent reliable use of features like busy_poll.
Recommendation
It is recommended to update the Linux kernel to a version containing the fix that resolves the race condition in the mana driver.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: net: mana: Fix race on per-CQ variable napi work_done After calling napi_complete_done(), the NAPIF_STATE_SCHED bit may be cleared, and another CPU can start napi thread and access per-CQ variable, cq->work_done. If the other thread (for example, from busy_poll) sets it to a value >= budget, this thread will continue to run when it should stop, and cause memory corruption and panic. To fix this issue, save the per-CQ work_done variable in a local variable before napi_complete_done(), so it won't be corrupted by a possible concurrent thread after napi_complete_done(). Also, add a flag bit to advertise to the NIC firmware: the NAPI work_done variable race is fixed, so the driver is able to reliably support features like busy_poll.