linux-kernel - [PATCH] uprobes: Use synchronize_rcu() not synchronize

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Message-ID: <20180809160553.469e1e32@gandalf.local.home>
Date:   Thu, 9 Aug 2018 16:05:53 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     "zhangwei(Jovi)" <jovi.zhangwei@...wei.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Oleg Nesterov <oleg@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        stable <stable@...r.kernel.org>
Subject: [PATCH] uprobes: Use synchronize_rcu() not synchronize_sched()


From: "Steven Rostedt (VMware)" <rostedt@...dmis.org>

While debugging another bug, I was looking at all the synchronize*()
functions being used in kernel/trace, and noticed that trace_uprobes was
using synchronize_sched(), with a comment to synchronize with
{u,ret}_probe_trace_func(). When looking at those functions, the data is
protected with "rcu_read_lock()" and not with "rcu_read_lock_sched()". This
is using the wrong synchronize_*() function.

Cc: stable@...r.kernel.org
Fixes: 70ed91c6ec7f8 ("tracing/uprobes: Support ftrace_event_file base multibuffer")
Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
---
 kernel/trace/trace_uprobe.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index bf89a51e740d..ac02fafc9f1b 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -952,7 +952,7 @@ probe_event_disable(struct trace_uprobe *tu, struct trace_event_file *file)
 
 		list_del_rcu(&link->list);
 		/* synchronize with u{,ret}probe_trace_func */
-		synchronize_sched();
+		synchronize_rcu();
 		kfree(link);
 
 		if (!list_empty(&tu->tp.files))
-- 
2.13.6