Hi,
Here is a bugfix (possible UAF) for fprobe found by Sashiko[1].
[1] https://sashiko.dev/#/bug/linux-e46bcd68-4a56-4f19-a255-e3772980e5e3
I think this fix is a short-term fix to make it safer. Eventually
I would like to replace all guard(rcu)() from fprobe with
preempt_disable_notrace(), because currently it introduces unneeded
overhead to fprobe.
- Introduce new call_rcu_tasks_rude() for async call.
- Add special non-preempt mode flag to rhashtable, which
uses call_rcu_tasks_rude() instead of call_rcu()
- Switching to use synchronize_rcu_tasks_rude() for unregistering.
- Replace call_rcu() with call_rcu_tasks_rude() in BPF.
But this is heavy depends on Tasks RCU, so I would like to check
with the RCU maintainers whether this idea aligns with the concept
behind Tasks RCU updates.
Thanks,
---
Masami Hiramatsu (Google) (1):
fprobe: Protect fprobe_return() with guard(rcu)()
kernel/trace/fprobe.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
--
Masami Hiramatsu (Google) <[email protected]>
