tracing/probes: Fix to update dynamic data counter if fetcharg uses it

commit e38e2c6a9efc435f9de344b7c91f7697e01b47d5 upstream.

Fix to update dynamic data counter ('dyndata') and max length ('maxlen')
only if the fetcharg uses the dynamic data. Also get out arg->dynamic
from unlikely(). This makes dynamic data address wrong if
process_fetch_insn() returns error on !arg->dynamic case.

Link: https://lore.kernel.org/all/168908494781.123124.8160245359962103684.stgit@devnote2/
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Link: https://lore.kernel.org/all/20230710233400.5aaf024e@gandalf.local.home/
Fixes: 9178412ddf5a ("tracing: probeevent: Return consumed bytes of dynamic area")
Cc: stable@vger.kernel.org
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/kernel/trace/trace_probe_tmpl.h b/kernel/trace/trace_probe_tmpl.h
index 5db3e69..c293a60 100644 (file)
--- a/kernel/trace/trace_probe_tmpl.h
+++ b/kernel/trace/trace_probe_tmpl.h
@@ -206,11 +206,13 @@ store_trace_args(void *data, struct trace_probe *tp, void *rec,
                if (unlikely(arg->dynamic))
                        *dl = make_data_loc(maxlen, dyndata - base);
                ret = process_fetch_insn(arg->code, rec, dl, base);
-               if (unlikely(ret < 0 && arg->dynamic)) {
-                       *dl = make_data_loc(0, dyndata - base);
-               } else {
-                       dyndata += ret;
-                       maxlen -= ret;
+               if (arg->dynamic) {
+                       if (unlikely(ret < 0)) {
+                               *dl = make_data_loc(0, dyndata - base);
+                       } else {
+                               dyndata += ret;
+                               maxlen -= ret;
+                       }
                }
        }
 }