linux-kernel - Re: [BUGFIX PATCH] tracing/kprobes: Fix to check notrace function with correct range

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Date:   Tue, 21 Aug 2018 09:42:49 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Masami Hiramatsu <mhiramat@...nel.org>
Cc:     Francis Deslauriers <francis.deslauriers@...icios.com>,
        peterz@...radead.org, mathieu.desnoyers@...icios.com,
        linux-kernel@...r.kernel.org, Michael Rodin <michael@...in.online>,
        Ravi Bangoria <ravi.bangoria@...ux.ibm.com>,
        linux-perf-users@...r.kernel.org,
        Arnaldo Carvalho de Melo <acme@...nel.org>
Subject: Re: [BUGFIX PATCH] tracing/kprobes: Fix to check notrace function
 with correct range

On Tue, 21 Aug 2018 22:04:57 +0900
Masami Hiramatsu <mhiramat@...nel.org> wrote:

> Fix within_notrace_func() to check notrace function correctly.
> 
> Since the ftrace_location_range(start, end) function checks
> the range inclusively (start <= ftrace-loc <= end), the end
> address must not include the entry address of next function.
> 
> However, within_notrace_func() uses kallsyms_lookup_size_offset()
> to get the function size and calculate the end address from
> adding the size to the entry address. This means the end address
> is the entry address of the next function.
> 
> In the result, within_notrace_func() fails to find notrace
> function if the next function of the target function is
> ftraced.
> 
> Let's subtract 1 from the end address so that ftrace_location_range()
> can check it correctly.
> 
> Fixes: commit 45408c4f9250 ("tracing: kprobes: Prohibit probing on notrace function")
> Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
> Reported-by: Michael Rodin <michael@...in.online>
> ---
>

Applied. Thanks Masami! I'll start testing this and send it upstream
when it's finished.

-- Steve