Messages in this thread | | | Date | Mon, 16 Oct 2017 23:02:06 +0200 | From | Daniel Borkmann <> | Subject | Re: [PATCH 3/3] bpf: Make sure that ->comm does not change under us. |
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On 10/16/2017 10:55 PM, Richard Weinberger wrote: > Am Montag, 16. Oktober 2017, 22:50:43 CEST schrieb Daniel Borkmann: >>> struct task_struct *task = current; >>> >>> + task_lock(task); >>> >>> strncpy(buf, task->comm, size); >>> >>> + task_unlock(task); >> >> Wouldn't this potentially lead to a deadlock? E.g. you attach yourself >> to task_lock() / spin_lock() / etc, and then the BPF prog triggers the >> bpf_get_current_comm() taking the lock again ... > > Yes, but doesn't the same apply to the use case when I attach to strncpy() > and run bpf_get_current_comm()?
You mean due to recursion? In that case trace_call_bpf() would bail out due to the bpf_prog_active counter.
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