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nfp: use struct_size() in kzalloc()

PATCH Applied Gustavo A. R. Silva 4 participants 6 messages Jan 31, 2019 – Feb 1, 2019

Subsystems (3)
Networking Network drivers Netronome Ethernet drivers
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Gustavo A. R. Silva

author
#0 lore raw

PATCH 1/1 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 <[email protected]>
---
 drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp_eth.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)
drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp_eth.c +1 -2
index 802c9224bb32..f6f028fa5db9 100644
@@ -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;
Signature · 1 line
2.20.1
Acked-by on v1 1/1
#1 lore raw
Quoted 11 lines · 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[];
};

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

Quoted 8 lines

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 <[email protected]>
Acked-by Jakub Kicinski <[email protected]>
author
#2 lore raw
Quoted 15 lines · Jakub Kicinski
Quoted 14 lines · 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[];
};

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:

Quoted 8 lines
Quoted 5 lines

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 <[email protected]>
Acked-by Jakub Kicinski <[email protected]>

Thanks, Jakub.

--
Gustavo

#3 lore raw
In reply to Gustavo A. R. Silva
Quoted 9 lines · 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[];
};
Quoted 8 lines

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/

Quoted 1 line · YueHaibing

Use kmemdup rather than duplicating its implementation

[]

drivers/net/wireless/intel/iwlwifi/iwl-nvm-parse.c

Quoted 1 line
drivers/net/wireless/intel/iwlwifi/iwl-nvm-parse.c +0 -0

[]

drivers/net/wireless/intel/iwlwifi/iwl-nvm-parse.c iwl_parse_nvm_mcc_info(struct device *dev, const struct iwl_cfg *cfg, · line 1198

Quoted 6 lines
drivers/net/wireless/intel/iwlwifi/iwl-nvm-parse.c +1 -2
@@ -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);
author
#4 lore raw

Hi Joe,

Quoted 15 lines · Joe Perches
Quoted 14 lines · 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[];
};

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:

Quoted 8 lines
Quoted 3 lines

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.

Quoted 16 lines

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

Quoted 1 line · YueHaibing

Use kmemdup rather than duplicating its implementation

[]

drivers/net/wireless/intel/iwlwifi/iwl-nvm-parse.c

Quoted 1 line
drivers/net/wireless/intel/iwlwifi/iwl-nvm-parse.c +0 -0

[]

drivers/net/wireless/intel/iwlwifi/iwl-nvm-parse.c iwl_parse_nvm_mcc_info(struct device *dev, const struct iwl_cfg *cfg, · line 1198

Quoted 6 lines
drivers/net/wireless/intel/iwlwifi/iwl-nvm-parse.c +1 -2
@@ -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

Quoted 3 lines
	copy_rd = kmemdup(regd, struct_size(regd, reg_rules, valid_rules),
			  GFP_KERNEL);

I agree.

Thanks
--
Gustavo

maintainer Applied
#5 lore raw
In reply to Gustavo A. R. Silva

From: "Gustavo A. R. Silva" <[email protected]>
Date: Wed, 30 Jan 2019 18:38:59 -0600

Quoted 11 lines

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);

Quoted 8 lines

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 <[email protected]>

Applied.