[RFC][PATCH 1/6] ftrace: Remove incorrect setting of glob search field

[Steven Rostedt]

From: "Steven Rostedt (VMware)" <rostedt@xxxxxxxxxxx>

__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@xxxxxxxxxxxxxxxxxx

Cc: stable@xxxxxxxxxxxxxxx
Cc: Dmitry Safonov <0x7f454c46@xxxxxxxxx>
Fixes: 3ba009297149f ("ftrace: Introduce ftrace_glob structure")
Reported-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
---
 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