tracing/filters: Fix MATCH_FULL filter matching for PTR_STRING

MATCH_FULL matching for PTR_STRING is not working correctly:

  # echo 'func == vt' > events/bkl/lock_kernel/filter
  # echo 1 > events/bkl/lock_kernel/enable
  ...
  # cat trace
   Xorg-1484  [000]  1973.392586: lock_kernel: ... func=vt_ioctl()
    gpm-1402  [001]  1974.027740: lock_kernel: ... func=vt_ioctl()

We should pass to regex.match(..., len) the length (including '\0')
of the source string instead of the length of the pattern string.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4B4E8763.5070707@cn.fujitsu.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 3 insertions, 4 deletions

diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index f364b085397..60c2a4efad4 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -211,8 +211,9 @@ static int filter_pred_pchar(struct filter_pred *pred, void *event,
 {
         char **addr = (char **)(event + pred->offset);
         int cmp, match;
+        int len = strlen(*addr) + 1;    /* including tailing '\0' */
 
-        cmp = pred->regex.match(*addr, &pred->regex, pred->regex.field_len);
+        cmp = pred->regex.match(*addr, &pred->regex, len);
 
         match = cmp ^ pred->not;
 
@@ -782,10 +783,8 @@ static int filter_add_pred(struct filter_parse_state *ps,
                         pred->regex.field_len = field->size;
                 } else if (field->filter_type == FILTER_DYN_STRING)
                         fn = filter_pred_strloc;
-                else {
+                else
                         fn = filter_pred_pchar;
-                        pred->regex.field_len = strlen(pred->regex.pattern);
-                }
         } else {
                 if (field->is_signed)
                         ret = strict_strtoll(pred->regex.pattern, 0, &val);