Bluetooth: Prevents buffer overflow on l2cap_ertm_reassembly_sdu()

The checks should be done before the the memcpy to avoid buffer
overflow.

Reported-by: João Paulo Rechi Vita <jprvita@profusion.mobi>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

diff --git a/net/bluetooth/l2cap.c b/net/bluetooth/l2cap.c
index fe663e9c66841c41965f4513a875c9774fdcd0b2..9ef01c32b3a224cefd9e40fdd3c99403c937b878 100644 (file)
--- a/net/bluetooth/l2cap.c
+++ b/net/bluetooth/l2cap.c
@@ -3470,12 +3470,12 @@ static int l2cap_ertm_reassembly_sdu(struct sock *sk, struct sk_buff *skb, u16 c
                if (!pi->sdu)
                        goto disconnect;
 
-               memcpy(skb_put(pi->sdu, skb->len), skb->data, skb->len);
-
                pi->partial_sdu_len += skb->len;
                if (pi->partial_sdu_len > pi->sdu_len)
                        goto drop;
 
+               memcpy(skb_put(pi->sdu, skb->len), skb->data, skb->len);
+
                break;
 
        case L2CAP_SDU_END:
@@ -3486,8 +3486,6 @@ static int l2cap_ertm_reassembly_sdu(struct sock *sk, struct sk_buff *skb, u16 c
                        goto disconnect;
 
                if (!(pi->conn_state & L2CAP_CONN_SAR_RETRY)) {
-                       memcpy(skb_put(pi->sdu, skb->len), skb->data, skb->len);
-
                        pi->partial_sdu_len += skb->len;
 
                        if (pi->partial_sdu_len > pi->imtu)
@@ -3495,6 +3493,8 @@ static int l2cap_ertm_reassembly_sdu(struct sock *sk, struct sk_buff *skb, u16 c
 
                        if (pi->partial_sdu_len != pi->sdu_len)
                                goto drop;
+
+                       memcpy(skb_put(pi->sdu, skb->len), skb->data, skb->len);
                }
 
                _skb = skb_clone(pi->sdu, GFP_ATOMIC);