[PATCH] hwmon: (ibmaem) Replace zero-length array with flexible-array member

From: Gustavo A. R. Silva
Date: Tue Feb 11 2020 - 19:18:20 EST


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@xxxxxxxxxxxxxx>
---
drivers/hwmon/ibmaem.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hwmon/ibmaem.c b/drivers/hwmon/ibmaem.c
index db63c1295cb2..fb052c2d9c34 100644
--- a/drivers/hwmon/ibmaem.c
+++ b/drivers/hwmon/ibmaem.c
@@ -232,7 +232,7 @@ struct aem_read_sensor_req {

struct aem_read_sensor_resp {
struct aem_iana_id id;
- u8 bytes[0];
+ u8 bytes[];
} __packed;

/* Data structures to talk to the IPMI layer */
--
2.25.0