[PATCH net-next] bnx2x: Use struct_size() in kzalloc()

[PATCH net-next] bnx2x: Use struct_size() in kzalloc()

[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;
    struct boo entry[];
};

size = sizeof(struct foo) + count * sizeof(struct boo);
instance = kzalloc(size, GFP_KERNEL)

Instead of leaving these open-coded and prone to type mistakes, we can
now use the new struct_size() helper:

instance = kzalloc(struct_size(instance, entry, count), GFP_KERNEL)

Notice that, in this case, variable fsz 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>
---
 drivers/net/ethernet/broadcom/bnx2x/bnx2x_vfpf.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_vfpf.c b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_vfpf.c
index 8e0a317b31f7..a9bdc21873d3 100644
--- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_vfpf.c
+++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_vfpf.c
@@ -1654,13 +1654,9 @@ static int bnx2x_vf_mbx_macvlan_list(struct bnx2x *bp,
 {
 	int i, j;
 	struct bnx2x_vf_mac_vlan_filters *fl = NULL;
-	size_t fsz;
 
-	fsz = tlv->n_mac_vlan_filters *
-	      sizeof(struct bnx2x_vf_mac_vlan_filter) +
-	      sizeof(struct bnx2x_vf_mac_vlan_filters);
-
-	fl = kzalloc(fsz, GFP_KERNEL);
+	fl = kzalloc(struct_size(fl, filters, tlv->n_mac_vlan_filters),
+		     GFP_KERNEL);
 	if (!fl)
 		return -ENOMEM;
 
-- 
2.20.1

Re: [PATCH net-next] bnx2x: Use struct_size() in kzalloc()

[David Miller]

From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Date: Thu, 7 Feb 2019 21:29:10 -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;
>     struct boo entry[];
> };
> 
> size = sizeof(struct foo) + count * sizeof(struct boo);
> instance = kzalloc(size, GFP_KERNEL)
> 
> Instead of leaving these open-coded and prone to type mistakes, we can
> now use the new struct_size() helper:
> 
> instance = kzalloc(struct_size(instance, entry, count), GFP_KERNEL)
> 
> Notice that, in this case, variable fsz 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>

Applied.