4.4-stable review patch. If anyone has any objections, please let me know.
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From: Steven Rostedt (VMware) rostedt@goodmis.org
commit 016f8ffc48cb01d1e7701649c728c5d2e737d295 upstream.
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.
Link: http://lkml.kernel.org/r/20180809160553.469e1e32@gandalf.local.home
Cc: stable@vger.kernel.org Fixes: 70ed91c6ec7f8 ("tracing/uprobes: Support ftrace_event_file base multibuffer") Acked-by: Oleg Nesterov oleg@redhat.com Signed-off-by: Steven Rostedt (VMware) rostedt@goodmis.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- kernel/trace/trace_uprobe.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/trace/trace_uprobe.c +++ b/kernel/trace/trace_uprobe.c @@ -969,7 +969,7 @@ probe_event_disable(struct trace_uprobe
list_del_rcu(&link->list); /* synchronize with u{,ret}probe_trace_func */ - synchronize_sched(); + synchronize_rcu(); kfree(link);
if (!list_empty(&tu->tp.files))