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Subject[PATCH 2/6] tracing: Fix parsing of globs with a wildcard at the beginning
From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>

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: 60f1d5e3bac44 ("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>
---
kernel/trace/trace_events_filter.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 61e7f0678d33..a764aec3c9a1 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -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;
}
--
2.15.1

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