[PATCH] ALSA: hda_codec: Replace zero-length array with flexible-array member

Gustavo A. R. Silva
2020-02-11T20:05:07Z

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>
---
sound/pci/hda/hda_codec.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sound/pci/hda/hda_codec.c b/sound/pci/hda/hda_codec.c
index 701a69d856f5..0fbca35509cd 100644
--- a/sound/pci/hda/hda_codec.c
+++ b/sound/pci/hda/hda_codec.c
@@ -102,7 +102,7 @@ struct hda_conn_list {
struct list_head list;
int len;
hda_nid_t nid;
- hda_nid_t conns[0];
+ hda_nid_t conns[];
};

/* look up the cached results */
--
2.25.0