The patch below does not apply to the 4.4-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 stable@vger.kernel.org.

thanks,

greg k-h

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

From 1a0aa991a6274161c95a844c58cfb801d681eb59 Mon Sep 17 00:00:00 2001

From: Masami Hiramatsu mhiramat@kernel.org Date: Tue, 12 May 2020 17:02:56 +0900 Subject: [PATCH] kprobes: Fix to protect kick_kprobe_optimizer() by kprobe_mutex

In kprobe_optimizer() kick_kprobe_optimizer() is called without kprobe_mutex, but this can race with other caller which is protected by kprobe_mutex.

To fix that, expand kprobe_mutex protected area to protect kick_kprobe_optimizer() call.

Link: http://lkml.kernel.org/r/158927057586.27680.5036330063955940456.stgit@devnot...

Fixes: cd7ebe2298ff ("kprobes: Use text_poke_smp_batch for optimizing") Cc: Ingo Molnar mingo@kernel.org Cc: "Gustavo A . R . Silva" gustavoars@kernel.org Cc: Anders Roxell anders.roxell@linaro.org Cc: "Naveen N . Rao" naveen.n.rao@linux.ibm.com Cc: Anil S Keshavamurthy anil.s.keshavamurthy@intel.com Cc: David Miller davem@davemloft.net Cc: Ingo Molnar mingo@elte.hu Cc: Peter Zijlstra peterz@infradead.org Cc: Ziqian SUN zsun@redhat.com Cc: stable@vger.kernel.org Signed-off-by: Masami Hiramatsu mhiramat@kernel.org Signed-off-by: Steven Rostedt (VMware) rostedt@goodmis.org

diff --git a/kernel/kprobes.c b/kernel/kprobes.c index ceb0e273bd69..0e185763578b 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -592,11 +592,12 @@ static void kprobe_optimizer(struct work_struct *work) mutex_unlock(&module_mutex); mutex_unlock(&text_mutex); cpus_read_unlock(); - mutex_unlock(&kprobe_mutex);

/* Step 5: Kick optimizer again if needed */ if (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list)) kick_kprobe_optimizer(); + + mutex_unlock(&kprobe_mutex); }

/* Wait for completing optimization and unoptimization */