Bluetooth: mgmt: Use struct_size() helper

PATCH In review Gustavo A. R. Silva 2 participants 2 messages Aug 30, 2019 – Sep 4, 2019

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Networking Network drivers Bluetooth drivers Bluetooth

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Gustavo A. R. Silva

author

2019-08-30 01:12 UTC #0 lore raw

PATCH 1/1 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 <[email protected]>

---
 net/bluetooth/mgmt.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

net/bluetooth/mgmt.c +2 -6

index 150114e33b20..acb7c6d5643f 100644
@@ -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);

Signature · 1 line

2.23.0

Marcel Holtmann

maintainer

2019-09-04 18:20 UTC #1 lore raw

Hi Gustavo,

Quoted 23 lines

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.

Quoted 6 lines

This code was detected with the help of Coccinelle.
Signed-off-by Gustavo A. R. Silva <[email protected]>
---
net/bluetooth/mgmt.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)

patch has been applied to bluetooth-next tree.

Regards

Marcel