tools lib traceevent: Fix get_field_str() for dynamic strings

BugLink: http://bugs.launchpad.net/bugs/1774063
[ Upstream commit d777f8de99b05d399c0e4e51cdce016f26bd971b ]

If a field is a dynamic string, get_field_str() returned just the
offset/size value and not the string. Have it parse the offset/size
correctly to return the actual string. Otherwise filtering fails when
trying to filter fields that are dynamic strings.

Reported-by: Gopanapalli Pradeep <prap_hai@yahoo.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20180112004823.146333275@goodmis.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/tools/lib/traceevent/parse-filter.c b/tools/lib/traceevent/parse-filter.c
index 315df0a70265291f2752ab5248e36b32a3e956b7..7b664fd1ebe8729f3507c534a8a45c54ec5ecbb0 100644 (file)
--- a/tools/lib/traceevent/parse-filter.c
+++ b/tools/lib/traceevent/parse-filter.c
@@ -1879,17 +1879,25 @@ static const char *get_field_str(struct filter_arg *arg, struct pevent_record *r
        struct pevent *pevent;
        unsigned long long addr;
        const char *val = NULL;
+       unsigned int size;
        char hex[64];
 
        /* If the field is not a string convert it */
        if (arg->str.field->flags & FIELD_IS_STRING) {
                val = record->data + arg->str.field->offset;
+               size = arg->str.field->size;
+
+               if (arg->str.field->flags & FIELD_IS_DYNAMIC) {
+                       addr = *(unsigned int *)val;
+                       val = record->data + (addr & 0xffff);
+                       size = addr >> 16;
+               }
 
                /*
                 * We need to copy the data since we can't be sure the field
                 * is null terminated.
                 */
-               if (*(val + arg->str.field->size - 1)) {
+               if (*(val + size - 1)) {
                        /* copy it */
                        memcpy(arg->str.buffer, val, arg->str.field->size);
                        /* the buffer is already NULL terminated */