[PATCH][next] brcmfmac: Use struct_size() in kzalloc()

[PATCH][next] brcmfmac: 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 reqsz 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/wireless/broadcom/brcm80211/brcmfmac/firmware.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.c
index 8209a42dea72..07b3ba949da5 100644
--- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.c
+++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.c
@@ -711,7 +711,6 @@ brcmf_fw_alloc_request(u32 chip, u32 chiprev,
 	size_t mp_path_len;
 	u32 i, j;
 	char end = '\0';
-	size_t reqsz;
 
 	for (i = 0; i < table_size; i++) {
 		if (mapping_table[i].chipid == chip &&
@@ -726,8 +725,7 @@ brcmf_fw_alloc_request(u32 chip, u32 chiprev,
 		return NULL;
 	}
 
-	reqsz = sizeof(*fwreq) + n_fwnames * sizeof(struct brcmf_fw_item);
-	fwreq = kzalloc(reqsz, GFP_KERNEL);
+	fwreq = kzalloc(struct_size(fwreq, items, n_fwnames), GFP_KERNEL);
 	if (!fwreq)
 		return NULL;
 
-- 
2.21.0

Re: [PATCH][next] brcmfmac: Use struct_size() in kzalloc()

[Kalle Valo]

"Gustavo A. R. Silva" <gustavo@embeddedor.com> wrote:

> 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 reqsz 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>

Patch applied to wireless-drivers-next.git, thanks.

0cf83903aad0 brcmfmac: Use struct_size() in kzalloc()

-- 
https://patchwork.kernel.org/patch/10884189/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches