[PATCH v2 1/5] Bluetooth: SCO: Fix not validating setsockopt user input

[Luiz Augusto von Dentz <luiz.dentz@xxxxxxxxx>]

From: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>

syzbot reported sco_sock_setsockopt() is copying data without
checking user input length.

BUG: KASAN: slab-out-of-bounds in copy_from_sockptr_offset
include/linux/sockptr.h:49 [inline]
BUG: KASAN: slab-out-of-bounds in copy_from_sockptr
include/linux/sockptr.h:55 [inline]
BUG: KASAN: slab-out-of-bounds in sco_sock_setsockopt+0xc0b/0xf90
net/bluetooth/sco.c:893
Read of size 4 at addr ffff88805f7b15a3 by task syz-executor.5/12578

Fixes: ad10b1a48754 ("Bluetooth: Add Bluetooth socket voice option")
Fixes: b96e9c671b05 ("Bluetooth: Add BT_DEFER_SETUP option to sco socket")
Fixes: 00398e1d5183 ("Bluetooth: Add support for BT_PKT_STATUS CMSG data for SCO connections")
Fixes: f6873401a608 ("Bluetooth: Allow setting of codec for HFP offload use case")
Reported-by: syzbot <syzkaller@xxxxxxxxxxxxxxxx>
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
---
 include/net/bluetooth/bluetooth.h |  9 +++++++++
 net/bluetooth/sco.c               | 23 ++++++++++-------------
 2 files changed, 19 insertions(+), 13 deletions(-)

diff --git a/include/net/bluetooth/bluetooth.h b/include/net/bluetooth/bluetooth.h
index 1ada4f85e982..431c907155e7 100644
--- a/include/net/bluetooth/bluetooth.h
+++ b/include/net/bluetooth/bluetooth.h
@@ -586,6 +586,15 @@ static inline struct sk_buff *bt_skb_sendmmsg(struct sock *sk,
 	return skb;
 }
 
+static inline int bt_copy_from_sockptr(void *dst, size_t dst_size,
+				       sockptr_t src, size_t src_size)
+{
+	if (dst_size > src_size)
+		return -EINVAL;
+
+	return copy_from_sockptr(dst, src, dst_size);
+}
+
 int bt_to_errno(u16 code);
 __u8 bt_status(int err);
 
diff --git a/net/bluetooth/sco.c b/net/bluetooth/sco.c
index 99c2b713d826..cc72f05d4f0e 100644
--- a/net/bluetooth/sco.c
+++ b/net/bluetooth/sco.c
@@ -839,7 +839,7 @@ static int sco_sock_setsockopt(struct socket *sock, int level, int optname,
 			       sockptr_t optval, unsigned int optlen)
 {
 	struct sock *sk = sock->sk;
-	int len, err = 0;
+	int err = 0;
 	struct bt_voice voice;
 	u32 opt;
 	struct bt_codecs *codecs;
@@ -858,10 +858,9 @@ static int sco_sock_setsockopt(struct socket *sock, int level, int optname,
 			break;
 		}
 
-		if (copy_from_sockptr(&opt, optval, sizeof(u32))) {
-			err = -EFAULT;
+		err = bt_copy_from_sockptr(&opt, sizeof(opt), optval, optlen);
+		if (err)
 			break;
-		}
 
 		if (opt)
 			set_bit(BT_SK_DEFER_SETUP, &bt_sk(sk)->flags);
@@ -878,11 +877,10 @@ static int sco_sock_setsockopt(struct socket *sock, int level, int optname,
 
 		voice.setting = sco_pi(sk)->setting;
 
-		len = min_t(unsigned int, sizeof(voice), optlen);
-		if (copy_from_sockptr(&voice, optval, len)) {
-			err = -EFAULT;
+		err = bt_copy_from_sockptr(&voice, sizeof(voice), optval,
+					   optlen);
+		if (err)
 			break;
-		}
 
 		/* Explicitly check for these values */
 		if (voice.setting != BT_VOICE_TRANSPARENT &&
@@ -905,10 +903,9 @@ static int sco_sock_setsockopt(struct socket *sock, int level, int optname,
 		break;
 
 	case BT_PKT_STATUS:
-		if (copy_from_sockptr(&opt, optval, sizeof(u32))) {
-			err = -EFAULT;
+		err = bt_copy_from_sockptr(&opt, sizeof(opt), optval, optlen);
+		if (err)
 			break;
-		}
 
 		if (opt)
 			set_bit(BT_SK_PKT_STATUS, &bt_sk(sk)->flags);
@@ -949,9 +946,9 @@ static int sco_sock_setsockopt(struct socket *sock, int level, int optname,
 			break;
 		}
 
-		if (copy_from_sockptr(buffer, optval, optlen)) {
+		err = bt_copy_from_sockptr(buffer, optlen, optval, optlen);
+		if (err) {
 			hci_dev_put(hdev);
-			err = -EFAULT;
 			break;
 		}
 
-- 
2.44.0