[PPP]: handle kmalloc failures and convert to using kzalloc

The PPP code contains two kmalloc()s followed by memset()s without
handling a possible memory allocation failure.  (Suggested by Joe
Perches).

And furthermore, conversions from kmalloc+memset to kzalloc.

[akpm@osdl.org: fix error-path leak]
[akpm@osdl.org: cleanups]
[paulus@samba.org: don't add useless printk and cardmap_destroy calls]
Signed-off-by: Panagiotis Issaris <takis@issaris.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ppp_generic.c

@@ -192,7 +192,7 @@ struct cardmap {
 	void *ptr[CARDMAP_WIDTH];
 };
 static void *cardmap_get(struct cardmap *map, unsigned int nr);
-static void cardmap_set(struct cardmap **map, unsigned int nr, void *ptr);
+static int cardmap_set(struct cardmap **map, unsigned int nr, void *ptr);
 static unsigned int cardmap_find_first_free(struct cardmap *map);
 static void cardmap_destroy(struct cardmap **map);
 
@@ -1995,10 +1995,9 @@ ppp_register_channel(struct ppp_channel *chan)
 {
 	struct channel *pch;
 
-	pch = kmalloc(sizeof(struct channel), GFP_KERNEL);
+	pch = kzalloc(sizeof(struct channel), GFP_KERNEL);
 	if (pch == 0)
 		return -ENOMEM;
-	memset(pch, 0, sizeof(struct channel));
 	pch->ppp = NULL;
 	pch->chan = chan;
 	chan->ppp = pch;
@@ -2408,13 +2407,12 @@ ppp_create_interface(int unit, int *retp)
 	int ret = -ENOMEM;
 	int i;
 
-	ppp = kmalloc(sizeof(struct ppp), GFP_KERNEL);
+	ppp = kzalloc(sizeof(struct ppp), GFP_KERNEL);
 	if (!ppp)
 		goto out;
 	dev = alloc_netdev(0, "", ppp_setup);
 	if (!dev)
 		goto out1;
-	memset(ppp, 0, sizeof(struct ppp));
 
 	ppp->mru = PPP_MRU;
 	init_ppp_file(&ppp->file, INTERFACE);
@@ -2454,11 +2452,16 @@ ppp_create_interface(int unit, int *retp)
 	}
 
 	atomic_inc(&ppp_unit_count);
-	cardmap_set(&all_ppp_units, unit, ppp);
+	ret = cardmap_set(&all_ppp_units, unit, ppp);
+	if (ret != 0)
+		goto out3;
+
 	mutex_unlock(&all_ppp_mutex);
 	*retp = 0;
 	return ppp;
 
+out3:
+	atomic_dec(&ppp_unit_count);
 out2:
 	mutex_unlock(&all_ppp_mutex);
 	free_netdev(dev);
@@ -2695,7 +2698,7 @@ static void *cardmap_get(struct cardmap *map, unsigned int nr)
 	return NULL;
 }
 
-static void cardmap_set(struct cardmap **pmap, unsigned int nr, void *ptr)
+static int cardmap_set(struct cardmap **pmap, unsigned int nr, void *ptr)
 {
 	struct cardmap *p;
 	int i;
@@ -2704,8 +2707,9 @@ static void cardmap_set(struct cardmap **pmap, unsigned int nr, void *ptr)
 	if (p == NULL || (nr >> p->shift) >= CARDMAP_WIDTH) {
 		do {
 			/* need a new top level */
-			struct cardmap *np = kmalloc(sizeof(*np), GFP_KERNEL);
-			memset(np, 0, sizeof(*np));
+			struct cardmap *np = kzalloc(sizeof(*np), GFP_KERNEL);
+			if (!np)
+				goto enomem;
 			np->ptr[0] = p;
 			if (p != NULL) {
 				np->shift = p->shift + CARDMAP_ORDER;
@@ -2719,8 +2723,9 @@ static void cardmap_set(struct cardmap **pmap, unsigned int nr, void *ptr)
 	while (p->shift > 0) {
 		i = (nr >> p->shift) & CARDMAP_MASK;
 		if (p->ptr[i] == NULL) {
-			struct cardmap *np = kmalloc(sizeof(*np), GFP_KERNEL);
-			memset(np, 0, sizeof(*np));
+			struct cardmap *np = kzalloc(sizeof(*np), GFP_KERNEL);
+			if (!np)
+				goto enomem;
 			np->shift = p->shift - CARDMAP_ORDER;
 			np->parent = p;
 			p->ptr[i] = np;
@@ -2735,6 +2740,9 @@ static void cardmap_set(struct cardmap **pmap, unsigned int nr, void *ptr)
 		set_bit(i, &p->inuse);
 	else
 		clear_bit(i, &p->inuse);
+	return 0;
+ enomem:
+	return -ENOMEM;
 }
 
 static unsigned int cardmap_find_first_free(struct cardmap *map)