[PATCH -tip V5 3/4] kprobes: Fix to protect kick_kprobe_optimizer() by kprobe_mutex

From: Masami Hiramatsu
Date: Thu Apr 02 2020 - 09:41:10 EST


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.

Fixes: cd7ebe2298ff ("kprobes: Use text_poke_smp_batch for optimizing")
Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
Changes in v5: Add Fixes and Cc:stable tags.
---
kernel/kprobes.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 38d9a5d7c8a4..6d76a6e3e1a5 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 */