[PATCH net-next] wimax/i2400m: use struct_size() helper

[PATCH net-next] wimax/i2400m: 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 foo {
    int stuff;
    void *entry[];
};

size = sizeof(struct foo) + count * sizeof(void *);
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);

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 drivers/net/wimax/i2400m/rx.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wimax/i2400m/rx.c b/drivers/net/wimax/i2400m/rx.c
index 0b602951ff6b..d28b96d06919 100644
--- a/drivers/net/wimax/i2400m/rx.c
+++ b/drivers/net/wimax/i2400m/rx.c
@@ -1260,8 +1260,8 @@ int i2400m_rx(struct i2400m *i2400m, struct sk_buff *skb)
 		goto error_msg_hdr_check;
 	result = -EIO;
 	num_pls = le16_to_cpu(msg_hdr->num_pls);
-	pl_itr = sizeof(*msg_hdr) +	/* Check payload descriptor(s) */
-		num_pls * sizeof(msg_hdr->pld[0]);
+	/* Check payload descriptor(s) */
+	pl_itr = struct_size(msg_hdr, pld, num_pls);
 	pl_itr = ALIGN(pl_itr, I2400M_PL_ALIGN);
 	if (pl_itr > skb_len) {	/* got all the payload descriptors? */
 		dev_err(dev, "RX: HW BUG? message too short (%u bytes) for "
-- 
2.20.1

Re: [PATCH net-next] wimax/i2400m: use struct_size() helper

[David Miller]

From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Date: Thu, 7 Feb 2019 21:22:17 -0600

> 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;
>     void *entry[];
> };
> 
> size = sizeof(struct foo) + count * sizeof(void *);
> 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);
> 
> This code was detected with the help of Coccinelle.
> 
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>

Applied.

Re: [PATCH net-next] wimax/i2400m: use struct_size() helper

[David Miller]

From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Date: Tue, 30 Apr 2019 22:27:32 -0500

> 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, replace code of the following form:
> 
> sizeof(*tx_msg) + le16_to_cpu(tx_msg->num_pls) * sizeof(tx_msg->pld[0]);
> 
> with:
> 
> struct_size(tx_msg, pld, le16_to_cpu(tx_msg->num_pls));
> 
> This code was detected with the help of Coccinelle.
> 
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>

Applied.

[PATCH net-next] wimax/i2400m: 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, replace code of the following form:

sizeof(*tx_msg) + le16_to_cpu(tx_msg->num_pls) * sizeof(tx_msg->pld[0]);

with:

struct_size(tx_msg, pld, le16_to_cpu(tx_msg->num_pls));

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 drivers/net/wimax/i2400m/tx.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/net/wimax/i2400m/tx.c b/drivers/net/wimax/i2400m/tx.c
index f20886ade1cc..ebd64e083726 100644
--- a/drivers/net/wimax/i2400m/tx.c
+++ b/drivers/net/wimax/i2400m/tx.c
@@ -640,8 +640,7 @@ void i2400m_tx_close(struct i2400m *i2400m)
 	 * figure out where the next TX message starts (and where the
 	 * offset to the moved header is).
 	 */
-	hdr_size = sizeof(*tx_msg)
-		+ le16_to_cpu(tx_msg->num_pls) * sizeof(tx_msg->pld[0]);
+	hdr_size = struct_size(tx_msg, pld, le16_to_cpu(tx_msg->num_pls));
 	hdr_size = ALIGN(hdr_size, I2400M_PL_ALIGN);
 	tx_msg->offset = I2400M_TX_PLD_SIZE - hdr_size;
 	tx_msg_moved = (void *) tx_msg + tx_msg->offset;
-- 
2.21.0