linux-kernel - [PATCH 4.15 199/202] ftrace: Remove incorrect setting of glob search field

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Message-Id: <20180215151723.055165995@linuxfoundation.org>
Date:   Thu, 15 Feb 2018 16:18:19 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Dmitry Safonov <0x7f454c46@...il.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Al Viro <viro@...IV.linux.org.uk>,
        "Steven Rostedt (VMware)" <rostedt@...dmis.org>
Subject: [PATCH 4.15 199/202] ftrace: Remove incorrect setting of glob search field

4.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Steven Rostedt (VMware) <rostedt@...dmis.org>

commit 7b6586562708d2b3a04fe49f217ddbadbbbb0546 upstream.

__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

Fixes: 3ba009297149f ("ftrace: Introduce ftrace_glob structure")
Reviewed-by: Dmitry Safonov <0x7f454c46@...il.com>
Reviewed-by: Masami Hiramatsu <mhiramat@...nel.org>
Reported-by: Al Viro <viro@...IV.linux.org.uk>
Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 kernel/trace/ftrace.c |    1 -
 1 file changed, 1 deletion(-)

--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -4456,7 +4456,6 @@ unregister_ftrace_function_probe_func(ch
 		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))