Re: [PATCH][next] Bluetooth: a2mp: Use struct_size() helper
From: Joe Perches <joe@perches.com>
Date: 2019-02-08 04:00:49
Also in:
linux-bluetooth, lkml
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.[]
quoted hunk ↗ jump to hunk
diff --git a/net/bluetooth/a2mp.c b/net/bluetooth/a2mp.c
[]
quoted hunk ↗ jump to hunk
@@ -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.