[PATCH][next] Bluetooth: mgmt: Use struct_size() helper

[PATCH][next] Bluetooth: mgmt: Use struct_size() helper

[Gustavo A. R. Silva]

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

Re: [PATCH][next] Bluetooth: mgmt: Use struct_size() helper

[Marcel Holtmann]

Hi Gustavo,

> 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(-)

patch has been applied to bluetooth-next tree.

Regards

Marcel

Re: [PATCH][next] Bluetooth: mgmt: Use struct_size() helper

[Marcel Holtmann]

Hi Gustavo,

> Make use of the struct_size() helper instead of an open-coded version
> in order to avoid any potential type mistakes, in particular in the
> context in which this code is being used.
> 
> So, change the following form:
> 
> sizeof(*rp) + (sizeof(rp->entry[0]) * count);
> 
> to :
> 
> struct_size(rp, entry, count)
> 
> 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, 3 insertions(+), 5 deletions(-)

patch has been applied to bluetooth-next tree.

Regards

Marcel

[PATCH][next] Bluetooth: mgmt: Use struct_size() helper

[Gustavo A. R. Silva]

Make use of the struct_size() helper instead of an open-coded version
in order to avoid any potential type mistakes, in particular in the
context in which this code is being used.

So, change the following form:

sizeof(*rp) + (sizeof(rp->entry[0]) * count);

to :

struct_size(rp, entry, count)

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, 3 insertions(+), 5 deletions(-)

diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
index ccce954f8146..1e2acaddcdfd 100644
--- a/net/bluetooth/mgmt.c
+++ b/net/bluetooth/mgmt.c
@@ -474,7 +474,6 @@ static int read_ext_index_list(struct sock *sk, struct hci_dev *hdev,
 {
 	struct mgmt_rp_read_ext_index_list *rp;
 	struct hci_dev *d;
-	size_t rp_len;
 	u16 count;
 	int err;
 
@@ -488,8 +487,7 @@ static int read_ext_index_list(struct sock *sk, struct hci_dev *hdev,
 			count++;
 	}
 
-	rp_len = sizeof(*rp) + (sizeof(rp->entry[0]) * count);
-	rp = kmalloc(rp_len, GFP_ATOMIC);
+	rp = kmalloc(struct_size(rp, entry, count), GFP_ATOMIC);
 	if (!rp) {
 		read_unlock(&hci_dev_list_lock);
 		return -ENOMEM;
@@ -525,7 +523,6 @@ static int read_ext_index_list(struct sock *sk, struct hci_dev *hdev,
 	}
 
 	rp->num_controllers = cpu_to_le16(count);
-	rp_len = sizeof(*rp) + (sizeof(rp->entry[0]) * count);
 
 	read_unlock(&hci_dev_list_lock);
 
@@ -538,7 +535,8 @@ static int read_ext_index_list(struct sock *sk, struct hci_dev *hdev,
 	hci_sock_clear_flag(sk, HCI_MGMT_UNCONF_INDEX_EVENTS);
 
 	err = mgmt_cmd_complete(sk, MGMT_INDEX_NONE,
-				MGMT_OP_READ_EXT_INDEX_LIST, 0, rp, rp_len);
+				MGMT_OP_READ_EXT_INDEX_LIST, 0, rp,
+				struct_size(rp, entry, count));
 
 	kfree(rp);
 
-- 
2.20.1