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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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