[PATCH] lib/ts_kmp: Replace zero-length array with flexible-array member

[PATCH] lib/ts_kmp: Replace zero-length array with flexible-array member

[Gustavo A. R. Silva]

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 76497732932f ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 lib/ts_kmp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/ts_kmp.c b/lib/ts_kmp.c
index ffbe66cbb0ed..9dd5e708630e 100644
--- a/lib/ts_kmp.c
+++ b/lib/ts_kmp.c
@@ -40,7 +40,7 @@ struct ts_kmp
 {
 	u8 *		pattern;
 	unsigned int	pattern_len;
-	unsigned int 	prefix_tbl[0];
+	unsigned int	prefix_tbl[];
 };
 
 static unsigned int kmp_find(struct ts_config *conf, struct ts_state *state)
-- 
2.25.0