Re: [BUGFIX PATCH bpf-next] error-injection: Fix to prohibit jump optimization

On 03/12/2018 03:06 PM, Masami Hiramatsu wrote:

On Mon, 12 Mar 2018 11:44:21 +0100
Daniel Borkmann [off-list ref] wrote:

quoted

On 03/12/2018 11:27 AM, Masami Hiramatsu wrote:

quoted

On Mon, 12 Mar 2018 19:00:49 +0900
Masami Hiramatsu [off-list ref] wrote:

quoted

Since the kprobe which was optimized by jump can not change
the execution path, the kprobe for error-injection must not
be optimized. To prohibit it, set a dummy post-handler as
officially stated in Documentation/kprobes.txt.

Note that trace-probe based BPF is not affected, because it
ensures the trace-probe is based on ftrace, which is not
jump optimized.

Thanks for the fix! I presume this should go via bpf instead of bpf-next
tree since 4b1a29a7f542 ("error-injection: Support fault injection framework")
is in Linus' tree as well. Unless there are objection I would rather route
it that way so it would be for 4.16.

Ah, right! It should go into 4.16. It should be applicable cleanly either tree
since there is only the above commit on kernel/fail_function.c :)

Applied to bpf tree, thanks Masami!