FAILED: patch "[PATCH] tracing: Fix bad hist from corrupting named_triggers list" failed to apply to 5.10-stable tree

The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y
git checkout FETCH_HEAD
git cherry-pick -x 6f86bdeab633a56d5c6dccf1a2c5989b6a5e323e
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2025030435-impurity-modular-98f0@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 6f86bdeab633a56d5c6dccf1a2c5989b6a5e323e Mon Sep 17 00:00:00 2001
From: Steven Rostedt <[email protected]>
Date: Thu, 27 Feb 2025 16:39:44 -0500
Subject: [PATCH] tracing: Fix bad hist from corrupting named_triggers list

The following commands causes a crash:

~# cd /sys/kernel/tracing/events/rcu/rcu_callback
~# echo 'hist:name=bad:keys=common_pid:onmax(bogus).save(common_pid)' > trigger
bash: echo: write error: Invalid argument
~# echo 'hist:name=bad:keys=common_pid' > trigger

Because the following occurs:

event_trigger_write() {

  trigger_process_regex() {
    event_hist_trigger_parse() {

      data = event_trigger_alloc(..);

      event_trigger_register(.., data) {
        cmd_ops->reg(.., data, ..) [hist_register_trigger()] {
          data->ops->init() [event_hist_trigger_init()] {
            save_named_trigger(name, data) {
              list_add(&data->named_list, &named_triggers);
            }
          }
        }
      }

      ret = create_actions(); (return -EINVAL)
      if (ret)
        goto out_unreg;
[..]
      ret = hist_trigger_enable(data, ...) {
        list_add_tail_rcu(&data->list, &file->triggers); <<<---- SKIPPED!!! (this is important!)
[..]
 out_unreg:
      event_hist_unregister(.., data) {
        cmd_ops->unreg(.., data, ..) [hist_unregister_trigger()] {
          list_for_each_entry(iter, &file->triggers, list) {
            if (!hist_trigger_match(data, iter, named_data, false))   <- never matches
                continue;
            [..]
            test = iter;
          }
          if (test && test->ops->free) <<<-- test is NULL

            test->ops->free(test) [event_hist_trigger_free()] {
              [..]
              if (data->name)
                del_named_trigger(data) {
                  list_del(&data->named_list);  <<<<-- NEVER gets removed!
                }
              }
           }
         }

         [..]
         kfree(data); <<<-- frees item but it is still on list

The next time a hist with name is registered, it causes an u-a-f bug and the kernel can crash.

Move the code around such that if event_trigger_register() succeeds, the next thing called is hist_trigger_enable() which adds it to the list.

A bunch of actions is called if get_named_trigger_data() returns false. But that doesn't need to be called after event_trigger_register(), so it can be moved up, allowing event_trigger_register() to be called just before hist_trigger_enable() keeping them together and allowing the file->triggers to be properly populated.

index 261163b00137..ad7419e24055 100644
@@ -6724,27 +6724,27 @@ static int event_hist_trigger_parse(struct event_command *cmd_ops,
 	if (existing_hist_update_only(glob, trigger_data, file))
 		goto out_free;
 
+	if (!get_named_trigger_data(trigger_data)) {
+
+		ret = create_actions(hist_data);
+		if (ret)
+			goto out_free;
+
+		if (has_hist_vars(hist_data) || hist_data->n_var_refs) {
+			ret = save_hist_vars(hist_data);
+			if (ret)
+				goto out_free;
+		}
+
+		ret = tracing_map_init(hist_data->map);
+		if (ret)
+			goto out_free;
+	}
+
 	ret = event_trigger_register(cmd_ops, file, glob, trigger_data);
 	if (ret < 0)
 		goto out_free;
 
-	if (get_named_trigger_data(trigger_data))
-		goto enable;
-
-	ret = create_actions(hist_data);
-	if (ret)
-		goto out_unreg;
-
-	if (has_hist_vars(hist_data) || hist_data->n_var_refs) {
-		ret = save_hist_vars(hist_data);
-		if (ret)
-			goto out_unreg;
-	}
-
-	ret = tracing_map_init(hist_data->map);
-	if (ret)
-		goto out_unreg;
-enable:
 	ret = hist_trigger_enable(trigger_data, file);
 	if (ret)
 		goto out_unreg;