mISDN: array underflow in open_bchannel()

There are two channels here.  User space starts counting channels at one
but in the kernel we start at zero.  If the user passes in a zero
channel that's invalid and could lead to memory corruption.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/isdn/hardware/mISDN/avmfritz.c

@@ -891,7 +891,7 @@ open_bchannel(struct fritzcard *fc, struct channel_req *rq)
 {
 	struct bchannel		*bch;
 
-	if (rq->adr.channel > 2)
+	if (rq->adr.channel == 0 || rq->adr.channel > 2)
 		return -EINVAL;
 	if (rq->protocol == ISDN_P_NONE)
 		return -EINVAL;

drivers/isdn/hardware/mISDN/hfcpci.c

@@ -1962,7 +1962,7 @@ open_bchannel(struct hfc_pci *hc, struct channel_req *rq)
 {
 	struct bchannel		*bch;
 
-	if (rq->adr.channel > 2)
+	if (rq->adr.channel == 0 || rq->adr.channel > 2)
 		return -EINVAL;
 	if (rq->protocol == ISDN_P_NONE)
 		return -EINVAL;

drivers/isdn/hardware/mISDN/hfcsusb.c

@@ -486,7 +486,7 @@ open_bchannel(struct hfcsusb *hw, struct channel_req *rq)
 {
 	struct bchannel		*bch;
 
-	if (rq->adr.channel > 2)
+	if (rq->adr.channel == 0 || rq->adr.channel > 2)
 		return -EINVAL;
 	if (rq->protocol == ISDN_P_NONE)
 		return -EINVAL;

drivers/isdn/hardware/mISDN/mISDNipac.c

@@ -1506,7 +1506,7 @@ open_bchannel(struct ipac_hw *ipac, struct channel_req *rq)
 {
 	struct bchannel		*bch;
 
-	if (rq->adr.channel > 2)
+	if (rq->adr.channel == 0 || rq->adr.channel > 2)
 		return -EINVAL;
 	if (rq->protocol == ISDN_P_NONE)
 		return -EINVAL;

drivers/isdn/hardware/mISDN/mISDNisar.c

@@ -1670,7 +1670,7 @@ isar_open(struct isar_hw *isar, struct channel_req *rq)
 {
 	struct bchannel		*bch;
 
-	if (rq->adr.channel > 2)
+	if (rq->adr.channel == 0 || rq->adr.channel > 2)
 		return -EINVAL;
 	if (rq->protocol == ISDN_P_NONE)
 		return -EINVAL;

drivers/isdn/hardware/mISDN/netjet.c

@@ -860,7 +860,7 @@ open_bchannel(struct tiger_hw *card, struct channel_req *rq)
 {
 	struct bchannel *bch;
 
-	if (rq->adr.channel > 2)
+	if (rq->adr.channel == 0 || rq->adr.channel > 2)
 		return -EINVAL;
 	if (rq->protocol == ISDN_P_NONE)
 		return -EINVAL;

drivers/isdn/hardware/mISDN/w6692.c

@@ -1015,7 +1015,7 @@ open_bchannel(struct w6692_hw *card, struct channel_req *rq)
 {
 	struct bchannel *bch;
 
-	if (rq->adr.channel > 2)
+	if (rq->adr.channel == 0 || rq->adr.channel > 2)
 		return -EINVAL;
 	if (rq->protocol == ISDN_P_NONE)
 		return -EINVAL;