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SubjectRe: [PATCH] Missing failure handling
On Thu, 20 Jul 2006 21:16:29 +0200
takis@lumumba.uhasselt.be (Panagiotis Issaris) wrote:

> From: Panagiotis Issaris <takis@issaris.org>
>
> 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.

OK...

> - struct cardmap *np = kmalloc(sizeof(*np), GFP_KERNEL);
> - memset(np, 0, sizeof(*np));
> + struct cardmap *np = kzalloc(sizeof(*np), GFP_KERNEL);
> + if (!np) {
> + printk(KERN_ERR "PPP: no memory (cardmap)\n");
> + return -ENOMEM;
> + }
> np->ptr[0] = p;
> if (p != NULL) {
> np->shift = p->shift + CARDMAP_ORDER;
> @@ -2719,8 +2727,11 @@ static void cardmap_set(struct cardmap *
> 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) {
> + printk(KERN_ERR "PPP: no memory (cardmap)\n");
> + return -ENOMEM;
> + }
> np->shift = p->shift - CARDMAP_ORDER;

But this leaks memory on errors.

It looks like cardmap_destroy() will handle a partially-constructed map,
so..

--- a/drivers/net/ppp_generic.c~ppp-handle-kmalloc-failures-leak-fix
+++ a/drivers/net/ppp_generic.c
@@ -2710,10 +2710,8 @@ static int cardmap_set(struct cardmap **
do {
/* need a new top level */
struct cardmap *np = kzalloc(sizeof(*np), GFP_KERNEL);
- if (!np) {
- printk(KERN_ERR "PPP: no memory (cardmap)\n");
- return -ENOMEM;
- }
+ if (!np)
+ goto enomem;
np->ptr[0] = p;
if (p != NULL) {
np->shift = p->shift + CARDMAP_ORDER;
@@ -2728,10 +2726,8 @@ static int cardmap_set(struct cardmap **
i = (nr >> p->shift) & CARDMAP_MASK;
if (p->ptr[i] == NULL) {
struct cardmap *np = kzalloc(sizeof(*np), GFP_KERNEL);
- if (!np) {
- printk(KERN_ERR "PPP: no memory (cardmap)\n");
- return -ENOMEM;
- }
+ if (!np)
+ goto enomem;
np->shift = p->shift - CARDMAP_ORDER;
np->parent = p;
p->ptr[i] = np;
@@ -2747,6 +2743,10 @@ static int cardmap_set(struct cardmap **
else
clear_bit(i, &p->inuse);
return 0;
+enomem:
+ printk(KERN_ERR "PPP: no memory (cardmap)\n");
+ cardmap_destroy(pmap);
+ return -ENOMEM;
}

static unsigned int cardmap_find_first_free(struct cardmap *map)
_
-
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