[PATCH] firmware: arm_scpi: replace zero-length array with flexible-array member

From: Gustavo A. R. Silva
Date: Tue Feb 11 2020 - 18:13:33 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/firmware/arm_scpi.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/firmware/arm_scpi.c b/drivers/firmware/arm_scpi.c
index c7d06a36b23a..0bc52876c79a 100644
--- a/drivers/firmware/arm_scpi.c
+++ b/drivers/firmware/arm_scpi.c
@@ -273,12 +273,12 @@ struct scpi_drvinfo {
struct scpi_shared_mem {
__le32 command;
__le32 status;
- u8 payload[0];
+ u8 payload[];
} __packed;

struct legacy_scpi_shared_mem {
__le32 status;
- u8 payload[0];
+ u8 payload[];
} __packed;

struct scp_capabilities {
--
2.25.0