From: Alexei Starovoitov <[email protected]>
Date: Thu, 28 May 2015 19:26:02 -0700
> Normally the program attachment place (like sockets, qdiscs) takes
> care of rcu protection and calls bpf_prog_put() after a grace period.
> The programs stored inside prog_array may not be attached anywhere,
> so prog_array needs to take care of preserving rcu protection.
> Otherwise bpf_tail_call() will race with bpf_prog_put().
> To solve that introduce bpf_prog_put_rcu() helper function and use
> it in 3 places where unattached program can decrement refcnt:
> closing program fd, deleting/replacing program in prog_array.
>
> Fixes: 04fd61ab36ec ("bpf: allow bpf programs to tail-call other bpf
> programs")
> Reported-by: Martin Schwidefsky <[email protected]>
> Signed-off-by: Alexei Starovoitov <[email protected]>
Applied, thank you.
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