kernel/trace: Fix cleanup logic of enable_trace_eprobe

The enable_trace_eprobe() function enables all event probes, attached
to given trace probe. If an error occurs in enabling one of the event
probes, all others should be roll backed. There is a bug in that roll
back logic - instead of all event probes, only the failed one is
disabled.

Link: https://lore.kernel.org/all/20230703042853.1427493-1-tz.stoyanov@gmail.com/
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Fixes: 7491e2c44278 ("tracing: Add a probe that attaches to trace events")
Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

diff --git a/kernel/trace/trace_eprobe.c b/kernel/trace/trace_eprobe.c
index 67e854979d53ec5bbc90641919031484bc4c9502..3f04f0ffe0d70920b2f9b9f3ab377cc64bfc5f10 100644 (file)
--- a/kernel/trace/trace_eprobe.c
+++ b/kernel/trace/trace_eprobe.c
@@ -675,6 +675,7 @@ static int enable_trace_eprobe(struct trace_event_call *call,
        struct trace_eprobe *ep;
        bool enabled;
        int ret = 0;
+       int cnt = 0;
 
        tp = trace_probe_primary_from_call(call);
        if (WARN_ON_ONCE(!tp))
@@ -698,12 +699,25 @@ static int enable_trace_eprobe(struct trace_event_call *call,
                if (ret)
                        break;
                enabled = true;
+               cnt++;
        }
 
        if (ret) {
                /* Failed to enable one of them. Roll back all */
-               if (enabled)
-                       disable_eprobe(ep, file->tr);
+               if (enabled) {
+                       /*
+                        * It's a bug if one failed for something other than memory
+                        * not being available but another eprobe succeeded.
+                        */
+                       WARN_ON_ONCE(ret != -ENOMEM);
+
+                       list_for_each_entry(pos, trace_probe_probe_list(tp), list) {
+                               ep = container_of(pos, struct trace_eprobe, tp);
+                               disable_eprobe(ep, file->tr);
+                               if (!--cnt)
+                                       break;
+                       }
+               }
                if (file)
                        trace_probe_remove_file(tp, file);
                else