Overview
About vulnerability
In the Linux kernel, the following vulnerability has been resolved:
bpf,fork: wipe ->bpf_storage before bailouts that access it
Currently, copy_process() can bail out to free_task() before p->bpf_storage has been initialized, with this call graph (shown here for the !CONFIG_MEMCG case):
copy_process dup_task_struct arch_dup_task_struct [copies the entire task_struct, including ->bpf_storage member] [RLIMIT_NPROC check fails] delayed_free_task free_task bpf_task_storage_free rcu_dereference(task->bpf_storage) bpf_local_storage_destroy
In this case, the nascent task’s ->bpf_storage member that bpf_local_storage_destroy() operates on is a plain copy of the parent’s ->bpf_storage pointer, not a real initialized pointer. This leads to badness (kernel hangs, UAF).
This is reachable as long as the process calling fork() has been inserted into a task storage map.
Details
- Affected product:
- AlmaLinux 9.2 ESU , Debian 10 ELS , TuxCare 9.6 ESU
- Affected packages:
- kernel @ 5.14.0 (+2 more)
Fixes
KernelCare state
Live-patch status from KernelCare for each operating system.
| Operating system | Status | Covered kernels |
|---|---|---|
| Debian 12 | Planned | — |
| Oracle Linux 9 UEK 7 | Planned | — |