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

Gustavo A. R. Silva
2020-02-11T20:48:48Z

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/bch.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/bch.c b/lib/bch.c
index 5db6d3a4c8a6..052d3fb753a0 100644
--- a/lib/bch.c
+++ b/lib/bch.c
@@ -102,7 +102,7 @@
*/
struct gf_poly {
unsigned int deg; /* polynomial degree */
- unsigned int c[0]; /* polynomial terms */
+ unsigned int c[]; /* polynomial terms */
};

/* given its degree, compute a polynomial size in bytes */
--
2.25.0