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SubjectRe: [RFC][PATCH 1/6] ftrace: Remove incorrect setting of glob search field
On Tue, 06 Feb 2018 17:43:39 -0500
Steven Rostedt <rostedt@goodmis.org> wrote:

> From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
>
> __unregister_ftrace_function_probe() will incorrectly parse the glob filter
> because it resets the search variable that was setup by filter_parse_regex().
>
> Al Viro reported this:
>
> After that call of filter_parse_regex() we could have func_g.search not
> equal to glob only if glob started with '!' or '*'. In the former case
> we would've buggered off with -EINVAL (not = 1). In the latter we
> would've set func_g.search equal to glob + 1, calculated the length of
> that thing in func_g.len and proceeded to reset func_g.search back to
> glob.
>
> Suppose the glob is e.g. *foo*. We end up with
> func_g.type = MATCH_MIDDLE_ONLY;
> func_g.len = 3;
> func_g.search = "*foo";
> Feeding that to ftrace_match_record() will not do anything sane - we
> will be looking for names containing "*foo" (->len is ignored for that
> one).
>
> Link: http://lkml.kernel.org/r/20180127031706.GE13338@ZenIV.linux.org.uk
>
> Cc: stable@vger.kernel.org
> Cc: Dmitry Safonov <0x7f454c46@gmail.com>
> Fixes: 3ba009297149f ("ftrace: Introduce ftrace_glob structure")
> Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>

Thank you!

> ---
> kernel/trace/ftrace.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> index dabd9d167d42..eac9ce2c57a2 100644
> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -4456,7 +4456,6 @@ unregister_ftrace_function_probe_func(char *glob, struct trace_array *tr,
> func_g.type = filter_parse_regex(glob, strlen(glob),
> &func_g.search, &not);
> func_g.len = strlen(func_g.search);
> - func_g.search = glob;
>
> /* we do not support '!' for function probes */
> if (WARN_ON(not))
> --
> 2.15.1
>
>


--
Masami Hiramatsu <mhiramat@kernel.org>

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