In the Linux kernel, the following vulnerability has been resolved: bpf: Wait for an RCU tasks grace period before freeing trampoline progs When a… (CVE-2026-98800)

The vulnerability involves the Linux kernel's BPF trampoline mechanism where programs detached from trampolines are freed after an RCU grace period. However, on preemptible kernels, tasks preempted just before acquiring the read lock in the trampoline could execute the program after it was freed, leading to a use-after-free and kernel memory corruption detected by KASAN. The fix ensures waiting for an RCU tasks grace period, which accounts for preempted tasks, before freeing such programs. This applies only to programs linked to trampolines, which are marked accordingly.

The vulnerability can cause kernel memory corruption and crashes due to use-after-free conditions when trampoline-linked BPF programs are freed prematurely. This can lead to system instability or denial of service. There is no indication of code execution or privilege escalation from the provided data.

A fix has been implemented in the Linux kernel to wait for an RCU tasks grace period before freeing trampoline-linked BPF programs, preventing use-after-free conditions. Users should update to the fixed kernel version once available. No additional mitigation steps are indicated.