Skip to contentSkip to conversation

lib: objagg: Use struct_size() in kzalloc()

PATCH Applied Gustavo A. R. Silva 3 participants 3 messages Jun 5, 2019 – Jun 6, 2019

Subsystems (4)
Networking Network drivers Library code Objagg
lore
Share & tools
lore

Gustavo A. R. Silva

author
#0 lore raw

PATCH 1/1 lib: objagg: 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 objagg_stats {
	...
        struct objagg_obj_stats_info stats_info[];
};

size = sizeof(*objagg_stats) + sizeof(objagg_stats->stats_info[0]) * count; 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, stats_info, count), GFP_KERNEL);

Notice that, in this case, variable alloc_size is not necessary, hence it is removed.

This code was detected with the help of Coccinelle.

Signed-off-by Gustavo A. R. Silva <[email protected]>
---
 lib/objagg.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)
lib/objagg.c +2 -4
index 576be22e86de..55621fb82e0a 100644
@@ -605,12 +605,10 @@ const struct objagg_stats *objagg_stats_get(struct objagg *objagg)
 {
 	struct objagg_stats *objagg_stats;
 	struct objagg_obj *objagg_obj;
-	size_t alloc_size;
 	int i;
 
-	alloc_size = sizeof(*objagg_stats) +
-		     sizeof(objagg_stats->stats_info[0]) * objagg->obj_count;
-	objagg_stats = kzalloc(alloc_size, GFP_KERNEL);
+	objagg_stats = kzalloc(struct_size(objagg_stats, stats_info,
+					   objagg->obj_count), GFP_KERNEL);
 	if (!objagg_stats)
 		return ERR_PTR(-ENOMEM);
Signature · 1 line
2.21.0
maintainer Acked-by on v1 1/1
#1 lore raw
Quoted 15 lines · Wed, Jun 05, 2019 at 04:45:16PM CEST, [email protected] 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 objagg_stats {
	...
       struct objagg_obj_stats_info stats_info[];
};

size = sizeof(*objagg_stats) + sizeof(objagg_stats->stats_info[0]) * count; 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:

Quoted 8 lines

instance = kzalloc(struct_size(instance, stats_info, count), GFP_KERNEL);

Notice that, in this case, variable alloc_size is not necessary, hence it is removed.

This code was detected with the help of Coccinelle.

Signed-off-by Gustavo A. R. Silva <[email protected]>
Acked-by Jiri Pirko <[email protected]>
maintainer Applied
#2 lore raw
In reply to Gustavo A. R. Silva

From: "Gustavo A. R. Silva" <[email protected]>
Date: Wed, 5 Jun 2019 09:45:16 -0500

Quoted 15 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 objagg_stats {
	...
        struct objagg_obj_stats_info stats_info[];
};

size = sizeof(*objagg_stats) + sizeof(objagg_stats->stats_info[0]) * count; 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:

Quoted 8 lines

instance = kzalloc(struct_size(instance, stats_info, count), GFP_KERNEL);

Notice that, in this case, variable alloc_size is not necessary, hence it is removed.

This code was detected with the help of Coccinelle.

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

Applied.