Commit 07234021 authored Feb 05, 2018 by Steven Rostedt (VMware)

tracing: Fix parsing of globs with a wildcard at the beginning

Al Viro reported:

    For substring - sure, but what about something like "*a*b" and "a*b"?
    AFAICS, filter_parse_regex() ends up with identical results in both
    cases - MATCH_GLOB and *search = "a*b".  And no way for the caller
    to tell one from another.

Testing this with the following:

 # cd /sys/kernel/tracing
 # echo '*raw*lock' > set_ftrace_filter
 bash: echo: write error: Invalid argument

With this patch:

 # echo '*raw*lock' > set_ftrace_filter
 # cat set_ftrace_filter
_raw_read_trylock
_raw_write_trylock
_raw_read_unlock
_raw_spin_unlock
_raw_write_unlock
_raw_spin_trylock
_raw_spin_lock
_raw_write_lock
_raw_read_lock

Al recommended not setting the search buffer to skip the first '*' unless we
know we are not using MATCH_GLOB. This implements his suggested logic.

Link: http://lkml.kernel.org/r/20180127170748.GF13338@ZenIV.linux.org.uk



Cc: stable@vger.kernel.org
Fixes: 60f1d5e3 ("ftrace: Support full glob matching")
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
Suggsted-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

parent 7b658656

kernel/trace/trace_events_filter.c

+4 −5

Original line number	Diff line number	Diff line
		@@ -400,7 +400,6 @@ enum regex_type filter_parse_regex(char buff, int len, char search, int not)
		for (i = 0; i < len; i++) {
		if (buff[i] == '*') {
		if (!i) {
		*search = buff + 1;
		type = MATCH_END_ONLY;
		} else if (i == len - 1) {
		if (type == MATCH_END_ONLY)
		@@ -410,14 +409,14 @@ enum regex_type filter_parse_regex(char buff, int len, char search, int not)
		buff[i] = 0;
		break;
		} else { /* pattern continues, use full glob */
		type = MATCH_GLOB;
		break;
		return MATCH_GLOB;
		}
		} else if (strchr("[?\\", buff[i])) {
		type = MATCH_GLOB;
		break;
		return MATCH_GLOB;
		}
		}
		if (buff[0] == '*')
		*search = buff + 1;

		return type;
		}