From 54b949b8f9ac32b7da35a0d4c0e4e6ddb767ef36 Mon Sep 17 00:00:00 2001
From: Anirudh Raghavendra <araghave@codeaurora.org>
Date: Wed, 29 Jul 2020 16:01:39 -0700
Subject: [PATCH] msm:adsprpc: Prevent use after free in
 fastrpc_set_process_info

Serialize kzalloc in fastrpc_set_process_info and prevent use
after free.

Change-Id: I02d62182a234ef40ce33165247fc578f6727d27a
Signed-off-by: Anirudh Raghavendra <araghave@codeaurora.org>
---
 drivers/char/adsprpc.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/char/adsprpc.c b/drivers/char/adsprpc.c
index 07b96023f518..39f13b097ce2 100644
--- a/drivers/char/adsprpc.c
+++ b/drivers/char/adsprpc.c
@@ -5119,7 +5119,15 @@ static int fastrpc_set_process_info(struct fastrpc_file *fl)
 	if (debugfs_root) {
 		buf_size = strlen(current->comm) + strlen("_")
 			+ strlen(strpid) + 1;
+
+		spin_lock(&fl->hlock);
+		if (fl->debug_buf) {
+			spin_unlock(&fl->hlock);
+			return err;
+		}
 		fl->debug_buf = kzalloc(buf_size, GFP_KERNEL);
+		spin_unlock(&fl->hlock);
+
 		if (!fl->debug_buf) {
 			err = -ENOMEM;
 			return err;