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* [PATCH][next] Bluetooth: hci_event: Use struct_size() helper
@ 2019-02-08  0:40 Gustavo A. R. Silva
  2019-02-08  4:02 ` Joe Perches
  2019-02-18 13:00 ` Marcel Holtmann
  0 siblings, 2 replies; 3+ messages in thread
From: Gustavo A. R. Silva @ 2019-02-08  0:40 UTC (permalink / raw)
  To: Marcel Holtmann, Johan Hedberg, David S. Miller
  Cc: linux-bluetooth, netdev, linux-kernel, 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(*ev) + ev->num_hndl * sizeof(struct hci_comp_pkts_info)

 to :

struct_size(ev, handles, ev->num_hndl)

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 net/bluetooth/hci_event.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index ac2826ce162b..609fd6871c5a 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -3556,8 +3556,8 @@ static void hci_num_comp_pkts_evt(struct hci_dev *hdev, struct sk_buff *skb)
 		return;
 	}
 
-	if (skb->len < sizeof(*ev) || skb->len < sizeof(*ev) +
-	    ev->num_hndl * sizeof(struct hci_comp_pkts_info)) {
+	if (skb->len < sizeof(*ev) ||
+	    skb->len < struct_size(ev, handles, ev->num_hndl)) {
 		BT_DBG("%s bad parameters", hdev->name);
 		return;
 	}
@@ -3644,8 +3644,8 @@ static void hci_num_comp_blocks_evt(struct hci_dev *hdev, struct sk_buff *skb)
 		return;
 	}
 
-	if (skb->len < sizeof(*ev) || skb->len < sizeof(*ev) +
-	    ev->num_hndl * sizeof(struct hci_comp_blocks_info)) {
+	if (skb->len < sizeof(*ev) ||
+	    skb->len < struct_size(ev, handles, ev->num_hndl)) {
 		BT_DBG("%s bad parameters", hdev->name);
 		return;
 	}
-- 
2.20.1


^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH][next] Bluetooth: hci_event: Use struct_size() helper
  2019-02-08  0:40 [PATCH][next] Bluetooth: hci_event: Use struct_size() helper Gustavo A. R. Silva
@ 2019-02-08  4:02 ` Joe Perches
  2019-02-18 13:00 ` Marcel Holtmann
  1 sibling, 0 replies; 3+ messages in thread
From: Joe Perches @ 2019-02-08  4:02 UTC (permalink / raw)
  To: Gustavo A. R. Silva, Marcel Holtmann, Johan Hedberg, David S. Miller
  Cc: linux-bluetooth, netdev, linux-kernel

On Thu, 2019-02-07 at 18:40 -0600, Gustavo A. R. Silva wrote:
> 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(*ev) + ev->num_hndl * sizeof(struct hci_comp_pkts_info)
> 
>  to :
> 
> struct_size(ev, handles, ev->num_hndl)
> 
> This code was detected with the help of Coccinelle.
[]
> diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
[]
> @@ -3556,8 +3556,8 @@ static void hci_num_comp_pkts_evt(struct hci_dev *hdev, struct sk_buff *skb)
>  		return;
>  	}
>  
> -	if (skb->len < sizeof(*ev) || skb->len < sizeof(*ev) +
> -	    ev->num_hndl * sizeof(struct hci_comp_pkts_info)) {
> +	if (skb->len < sizeof(*ev) ||
> +	    skb->len < struct_size(ev, handles, ev->num_hndl)) {
>  		BT_DBG("%s bad parameters", hdev->name);
>  		return;
>  	}
> @@ -3644,8 +3644,8 @@ static void hci_num_comp_blocks_evt(struct hci_dev *hdev, struct sk_buff *skb)
>  		return;
>  	}
>  
> -	if (skb->len < sizeof(*ev) || skb->len < sizeof(*ev) +
> -	    ev->num_hndl * sizeof(struct hci_comp_blocks_info)) {
> +	if (skb->len < sizeof(*ev) ||
> +	    skb->len < struct_size(ev, handles, ev->num_hndl)) {

Unless these are in a real fast path where skb->len < sizeof(*ev)
is pretty likely, it seems a bit redundant as the multiplication
is pretty cheap and num_hndl is unsigned (actually __u8)

This could/should be simply

	if (skb->len < struct_size(...))



^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH][next] Bluetooth: hci_event: Use struct_size() helper
  2019-02-08  0:40 [PATCH][next] Bluetooth: hci_event: Use struct_size() helper Gustavo A. R. Silva
  2019-02-08  4:02 ` Joe Perches
@ 2019-02-18 13:00 ` Marcel Holtmann
  1 sibling, 0 replies; 3+ messages in thread
From: Marcel Holtmann @ 2019-02-18 13:00 UTC (permalink / raw)
  To: Gustavo A. R. Silva
  Cc: Johan Hedberg, David S. Miller, linux-bluetooth, netdev, linux-kernel

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(*ev) + ev->num_hndl * sizeof(struct hci_comp_pkts_info)
> 
> to :
> 
> struct_size(ev, handles, ev->num_hndl)
> 
> This code was detected with the help of Coccinelle.
> 
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
> ---
> net/bluetooth/hci_event.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)

patch has been applied to bluetooth-next tree.

Regards

Marcel


^ permalink raw reply	[flat|nested] 3+ messages in thread

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2019-02-08  0:40 [PATCH][next] Bluetooth: hci_event: Use struct_size() helper Gustavo A. R. Silva
2019-02-08  4:02 ` Joe Perches
2019-02-18 13:00 ` Marcel Holtmann

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