lkml.org 
[lkml]   [2019]   [Feb]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [PATCH][next] Bluetooth: a2mp: Use struct_size() helper
    From
    Date
    On Thu, 2019-02-07 at 18:28 -0600, Gustavo A. R. Silva wrote:
    > One of the more common cases of allocation size calculations is finding
    > the size of a structure that has a zero-sized array at the end, along
    > with memory for some number of elements for that array. For example:
    >
    > struct foo {
    > int stuff;
    > struct boo entry[];
    > };
    >
    > size = sizeof(struct foo) + count * sizeof(struct boo);
    > instance = alloc(size, GFP_KERNEL)
    >
    > Instead of leaving these open-coded and prone to type mistakes, we can
    > now use the new struct_size() helper:
    >
    > size = struct_size(instance, entry, count);
    > instance = alloc(size, GFP_KERNEL)
    >
    > This code was detected with the help of Coccinelle.
    []
    > diff --git a/net/bluetooth/a2mp.c b/net/bluetooth/a2mp.c
    []
    > @@ -174,7 +174,7 @@ static int a2mp_discover_req(struct amp_mgr *mgr, struct sk_buff *skb,
    > num_ctrl++;
    > }
    >
    > - len = num_ctrl * sizeof(struct a2mp_cl) + sizeof(*rsp);
    > + len = struct_size(rsp, cl, num_ctrl);
    > rsp = kmalloc(len, GFP_ATOMIC);
    > if (!rsp) {
    > read_unlock(&hci_dev_list_lock);

    At least a weakness in this code is len is u16
    and struct_size is size_t so there's a size
    truncation possible.


    \
     
     \ /
      Last update: 2019-02-08 05:01    [W:6.382 / U:0.044 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site