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lib: objagg: Replace zero-length arrays with flexible-array member

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The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertenly introduced[3] to the codebase from now on.

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Gustavo A. R. Silva 2020-02-11 14:53:56 -06:00 committed by David S. Miller
parent d71151a39c
commit 1f4c51de33
1 changed files with 2 additions and 2 deletions
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lib/objagg.c
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@ -28,7 +28,7 @@ struct objagg_hints_node {
struct objagg_hints_node *parent;
unsigned int root_id;
struct objagg_obj_stats_info stats_info;
unsigned long obj[0];
unsigned long obj[];
};
static struct objagg_hints_node *
@ -66,7 +66,7 @@ struct objagg_obj {
* including nested objects
*/
struct objagg_obj_stats stats;
unsigned long obj[0];
unsigned long obj[];
};
static unsigned int objagg_obj_ref_inc(struct objagg_obj *objagg_obj)