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mlxsw: spectrum_acl_bloom_filter: use struct_size() in kzalloc()

PATCH In review Gustavo A. R. Silva 2 participants 3 messages Dec 24, 2018

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Networking Network drivers Mellanox Ethernet switch drivers
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Gustavo A. R. Silva

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#0 lore raw

PATCH 1/1 mlxsw: spectrum_acl_bloom_filter: 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;
    void *entry[];
};

instance = kzalloc(sizeof(struct foo) + sizeof(void *) * count, 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 issue was detected with the help of Coccinelle.

Signed-off-by Gustavo A. R. Silva <[email protected]>
---
 .../net/ethernet/mellanox/mlxsw/spectrum_acl_bloom_filter.c   | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_bloom_filter.c +2 -2
index 505b87846acc..f5c381dcb015 100644
@@ -234,8 +234,8 @@ mlxsw_sp_acl_bf_init(struct mlxsw_sp *mlxsw_sp, unsigned int num_erp_banks)
 	 * is 2^ACL_MAX_BF_LOG
 	 */
 	bf_bank_size = 1 << MLXSW_CORE_RES_GET(mlxsw_sp->core, ACL_MAX_BF_LOG);
-	bf = kzalloc(sizeof(*bf) + bf_bank_size * num_erp_banks *
-		     sizeof(*bf->refcnt), GFP_KERNEL);
+	bf = kzalloc(struct_size(bf, refcnt, bf_bank_size * num_erp_banks),
+		     GFP_KERNEL);
 	if (!bf)
 		return ERR_PTR(-ENOMEM);
Signature · 1 line
2.17.0
Reviewed-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;
    void *entry[];
};

instance = kzalloc(sizeof(struct foo) + sizeof(void *) * count, 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 issue was detected with the help of Coccinelle.

Signed-off-by Gustavo A. R. Silva <[email protected]>
Reviewed-by Ido Schimmel <[email protected]>

But net-next is closed (http://vger.kernel.org/~davem/net-next.html) and this isn't a bug fix. Can you please re-submit when net-next opens again? Alternatively, I can apply the patch to my mlxsw queue and submit in your stead. Let me know what you prefer.

Thanks!

author
#2 lore raw
Quoted 19 lines · Ido Schimmel
Quoted 18 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;
     void *entry[];
};

instance = kzalloc(sizeof(struct foo) + sizeof(void *) * count, 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 issue was detected with the help of Coccinelle.

Quoted 9 lines
Quoted 1 line
Signed-off-by Gustavo A. R. Silva <[email protected]>
Reviewed-by Ido Schimmel <[email protected]>

But net-next is closed (http://vger.kernel.org/~davem/net-next.html) and this isn't a bug fix. Can you please re-submit when net-next opens again? Alternatively, I can apply the patch to my mlxsw queue and submit in your stead. Let me know what you prefer.

Oh yeah. I forgot net close net-next during the merge window. I'll re-submit it in two weeks then. I'll add your Reviewed-by.

Happy holiday.

Thanks
--
Gustavo