[PATCH net-next] nfp: use struct_size() in kzalloc()

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[];
};

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

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <redacted>
---
 drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp_eth.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp_eth.c b/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp_eth.c
index 802c9224bb32..f6f028fa5db9 100644
--- a/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp_eth.c
+++ b/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp_eth.c

@@ -269,8 +269,7 @@ __nfp_eth_read_ports(struct nfp_cpp *cpp, struct nfp_nsp *nsp)
 		goto err;
 	}
 
-	table = kzalloc(sizeof(*table) +
-			sizeof(struct nfp_eth_table_port) * cnt, GFP_KERNEL);
+	table = kzalloc(struct_size(table, ports, cnt), GFP_KERNEL);
 	if (!table)
 		goto err;
 

-- 
2.20.1

On Wed, 30 Jan 2019 18:38:59 -0600, Gustavo A. R. Silva 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[];
};

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

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <redacted>

Acked-by: Jakub Kicinski <redacted>

On 1/30/19 6:52 PM, Jakub Kicinski wrote:

On Wed, 30 Jan 2019 18:38:59 -0600, Gustavo A. R. Silva wrote:

quoted

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[];
};

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

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <redacted>

Acked-by: Jakub Kicinski <redacted>

Thanks, Jakub.

--
Gustavo

On Wed, 2019-01-30 at 18:38 -0600, Gustavo A. R. Silva 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[];
};

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

This code was detected with the help of Coccinelle.

Might be useful to augment the script to include cases
where the computed size is saved to a temporary and
that temporary is used ala:

https://patchwork.kernel.org/patch/10782453/

On Sat, 2019-01-26 at 20:42 +0800, YueHaibing wrote:

Use kmemdup rather than duplicating its implementation

[]

[]

This should probably be

	copy_rd = kmemdup(regd, struct_size(regd, reg_rules, valid_rules),
			  GFP_KERNEL);

Hi Joe,

On 1/31/19 11:11 AM, Joe Perches wrote:

On Wed, 2019-01-30 at 18:38 -0600, Gustavo A. R. Silva wrote:

quoted

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[];
};

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

This code was detected with the help of Coccinelle.

Might be useful to augment the script to include cases
where the computed size is saved to a temporary and
that temporary is used ala:

Yep. That's already on my list.

https://patchwork.kernel.org/patch/10782453/

On Sat, 2019-01-26 at 20:42 +0800, YueHaibing wrote:

quoted

Use kmemdup rather than duplicating its implementation

[]

quoted

diff --git a/drivers/net/wireless/intel/iwlwifi/iwl-nvm-parse.c b/drivers/net/wireless/intel/iwlwifi/iwl-nvm-parse.c

[]

quoted

@@ -1196,13 +1196,9 @@ iwl_parse_nvm_mcc_info(struct device *dev, const struct iwl_cfg *cfg,
 	regd_to_copy = sizeof(struct ieee80211_regdomain) +
 		valid_rules * sizeof(struct ieee80211_reg_rule);
-	copy_rd = kzalloc(regd_to_copy, GFP_KERNEL);
-	if (!copy_rd) {
+	copy_rd = kmemdup(regd, regd_to_copy, GFP_KERNEL);

This should probably be

	copy_rd = kmemdup(regd, struct_size(regd, reg_rules, valid_rules),
			  GFP_KERNEL);

I agree.

Thanks
--
Gustavo

From: "Gustavo A. R. Silva" <redacted>
Date: Wed, 30 Jan 2019 18:38:59 -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[];
};

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

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <redacted>

Applied.