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Subject[PATCH][next] Bluetooth: mgmt: Use struct_size() helper
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 mgmt_rp_get_connections {
...
struct mgmt_addr_info addr[0];
} __packed;

Make use of the struct_size() helper instead of an open-coded version
in order to avoid any potential type mistakes.

So, replace the following form:

sizeof(*rp) + (i * sizeof(struct mgmt_addr_info));

with:

struct_size(rp, addr, i)

Also, notice that, in this case, variable rp_len is not necessary,
hence it is removed.

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
net/bluetooth/mgmt.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
index 150114e33b20..acb7c6d5643f 100644
--- a/net/bluetooth/mgmt.c
+++ b/net/bluetooth/mgmt.c
@@ -2588,7 +2588,6 @@ static int get_connections(struct sock *sk, struct hci_dev *hdev, void *data,
{
struct mgmt_rp_get_connections *rp;
struct hci_conn *c;
- size_t rp_len;
int err;
u16 i;

@@ -2608,8 +2607,7 @@ static int get_connections(struct sock *sk, struct hci_dev *hdev, void *data,
i++;
}

- rp_len = sizeof(*rp) + (i * sizeof(struct mgmt_addr_info));
- rp = kmalloc(rp_len, GFP_KERNEL);
+ rp = kmalloc(struct_size(rp, addr, i), GFP_KERNEL);
if (!rp) {
err = -ENOMEM;
goto unlock;
@@ -2629,10 +2627,8 @@ static int get_connections(struct sock *sk, struct hci_dev *hdev, void *data,
rp->conn_count = cpu_to_le16(i);

/* Recalculate length in case of filtered SCO connections, etc */
- rp_len = sizeof(*rp) + (i * sizeof(struct mgmt_addr_info));
-
err = mgmt_cmd_complete(sk, hdev->id, MGMT_OP_GET_CONNECTIONS, 0, rp,
- rp_len);
+ struct_size(rp, addr, i));

kfree(rp);

--
2.23.0
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