Messages in this thread | | | Date | Fri, 12 Mar 2021 18:07:10 +0100 | From | Oleg Nesterov <> | Subject | Re: [PATCH] ptrace: Allow other threads to access tracee |
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On 03/11, Jim Newsome wrote: > > I suppose even if the corruption of the register-values-themselves is > acceptable, some synchronization may be needed to avoid the possibility > of corrupting the kernel's data structures?
Yes, the kernel can crash. Just look at the comment above ptrace_freeze_traced(). The kernel assumes that the tracee is frozen, in particular it can't exit. Say, ptrace_peek_siginfo() can crash the tracee exits and clears ->sighand, and this can obviously happen if another thread does PTRACE_CONT + SIGKILL.
> Is it "just" a matter of adding some locking? Would a relatively coarse > lock on the target task over the duration of the ptrace call
Yes I think needs a mutex in task_struct. But honestly I am not sure it makes sense.... I dunno.
> (which I > believe is always non-blocking?)
Why? It is blocking.
Oleg.
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