mISDN: prevent possible NULL pointer dereference

A return value of the bchannel_get_rxbuf() function is compared with the
positive ENOMEM value instead of the negative -ENOMEM value to detect a
memory allocation problem. Thus, after a possible memory allocation
failure the bc->bch.rx_skb will be NULL which will lead to a NULL
pointer dereference.

Signed-off-by: Anton Protopopov <a.s.protopopov@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/isdn/hardware/mISDN/netjet.c b/drivers/isdn/hardware/mISDN/netjet.c
index 8e2944784e0004e4fc933d691607c4e822c3bf66..afde4edef9ae895fa009fb5ad7305cc13af2c22e 100644 (file)
--- a/drivers/isdn/hardware/mISDN/netjet.c
+++ b/drivers/isdn/hardware/mISDN/netjet.c
@@ -392,7 +392,7 @@ read_dma(struct tiger_ch *bc, u32 idx, int cnt)
        }
        stat = bchannel_get_rxbuf(&bc->bch, cnt);
        /* only transparent use the count here, HDLC overun is detected later */
-       if (stat == ENOMEM) {
+       if (stat == -ENOMEM) {
                pr_warning("%s.B%d: No memory for %d bytes\n",
                           card->name, bc->bch.nr, cnt);
                return;