From 2b70d4f9b20635ac328836e50d183632e1930f94 Mon Sep 17 00:00:00 2001
From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Fri, 7 Jan 2022 10:16:44 +0300
Subject: [PATCH] Bluetooth: L2CAP: uninitialized variables in l2cap_sock_setsockopt()
Git-commit: 2b70d4f9b20635ac328836e50d183632e1930f94
Patch-mainline: v5.17-rc1
References: git-fixes

The "opt" variable is a u32, but on some paths only the top bytes
were initialized and the others contained random stack data.

Fixes: a7b75c5a8c41 ("net: pass a sockptr_t into ->setsockopt")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 net/bluetooth/l2cap_sock.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c
index 188e4d4813b0..ca8f07f3542b 100644
--- a/net/bluetooth/l2cap_sock.c
+++ b/net/bluetooth/l2cap_sock.c
@@ -904,6 +904,8 @@ static int l2cap_sock_setsockopt(struct socket *sock, int level, int optname,
 	struct l2cap_conn *conn;
 	int len, err = 0;
 	u32 opt;
+	u16 mtu;
+	u8 mode;
 
 	BT_DBG("sk %p", sk);
 
@@ -1086,16 +1088,16 @@ static int l2cap_sock_setsockopt(struct socket *sock, int level, int optname,
 			break;
 		}
 
-		if (copy_from_sockptr(&opt, optval, sizeof(u16))) {
+		if (copy_from_sockptr(&mtu, optval, sizeof(u16))) {
 			err = -EFAULT;
 			break;
 		}
 
 		if (chan->mode == L2CAP_MODE_EXT_FLOWCTL &&
 		    sk->sk_state == BT_CONNECTED)
-			err = l2cap_chan_reconfigure(chan, opt);
+			err = l2cap_chan_reconfigure(chan, mtu);
 		else
-			chan->imtu = opt;
+			chan->imtu = mtu;
 
 		break;
 
@@ -1117,14 +1119,14 @@ static int l2cap_sock_setsockopt(struct socket *sock, int level, int optname,
 			break;
 		}
 
-		if (copy_from_sockptr(&opt, optval, sizeof(u8))) {
+		if (copy_from_sockptr(&mode, optval, sizeof(u8))) {
 			err = -EFAULT;
 			break;
 		}
 
-		BT_DBG("opt %u", opt);
+		BT_DBG("mode %u", mode);
 
-		err = l2cap_set_mode(chan, opt);
+		err = l2cap_set_mode(chan, mode);
 		if (err)
 			break;
 
-- 
2.31.1