Thread (6 messages) 6 messages, 2 authors, 2025-07-28
STALE325d LANDED

[PATCH 2/2] rv: Fix wrong type cast in reactors_show() and monitor_reactor_show()

From: Nam Cao <hidden>
Date: 2025-07-27 17:31:23
Also in: lkml
Subsystem: runtime verification (rv), the rest, tracing · Maintainers: Steven Rostedt, Gabriele Monaco, Linus Torvalds, Masami Hiramatsu

Argument 'p' of reactors_show() and monitor_reactor_show() is not a pointer
to struct rv_reactor, it is actually a pointer to the list_head inside
struct rv_reactor. Therefore it's wrong to cast 'p' to struct rv_reactor *.

This wrong type cast has been there since the beginning. But it still
worked because the list_head was the first field in struct rv_reactor_def.
This is no longer true since commit 3d3c376118b5 ("rv: Merge struct
rv_reactor_def into struct rv_reactor") moved the list_head, and this wrong
type cast became a functional problem.

Properly use container_of() instead.

Fixes: 3d3c376118b5 ("rv: Merge struct rv_reactor_def into struct rv_reactor")
Signed-off-by: Nam Cao <redacted>
---
 kernel/trace/rv/rv_reactors.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/trace/rv/rv_reactors.c b/kernel/trace/rv/rv_reactors.c
index 106f2c4740f2..d32859fec238 100644
--- a/kernel/trace/rv/rv_reactors.c
+++ b/kernel/trace/rv/rv_reactors.c
@@ -86,7 +86,7 @@ static struct rv_reactor *get_reactor_rdef_by_name(char *name)
  */
 static int reactors_show(struct seq_file *m, void *p)
 {
-	struct rv_reactor *reactor = p;
+	struct rv_reactor *reactor = container_of(p, struct rv_reactor, list);
 
 	seq_printf(m, "%s\n", reactor->name);
 	return 0;
@@ -139,7 +139,7 @@ static const struct file_operations available_reactors_ops = {
 static int monitor_reactor_show(struct seq_file *m, void *p)
 {
 	struct rv_monitor *mon = m->private;
-	struct rv_reactor *reactor = p;
+	struct rv_reactor *reactor = container_of(p, struct rv_reactor, list);
 
 	if (mon->reactor == reactor)
 		seq_printf(m, "[%s]\n", reactor->name);
-- 
2.39.5
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