From 683cc86d812cace1ead68c489a52a1533498302c Mon Sep 17 00:00:00 2001
From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Date: Wed, 12 Feb 2020 13:28:07 -0600
Subject: [PATCH] Bluetooth: btintel: Replace zero-length array with flexible-array member
Git-commit: 683cc86d812cace1ead68c489a52a1533498302c
Patch-mainline: v5.7-rc1
References: jsc#SLE-13430
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.
Also, notice that, dynamic memory allocations won't be affected by
this change:
"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]
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>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/bluetooth/btintel.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/bluetooth/btintel.c b/drivers/bluetooth/btintel.c
index 62e781a18bf0..6a0e2c5a8beb 100644
--- a/drivers/bluetooth/btintel.c
+++ b/drivers/bluetooth/btintel.c
@@ -376,13 +376,13 @@ struct ibt_cp_reg_access {
__le32 addr;
__u8 mode;
__u8 len;
- __u8 data[0];
+ __u8 data[];
} __packed;
struct ibt_rp_reg_access {
__u8 status;
__le32 addr;
- __u8 data[0];
+ __u8 data[];
} __packed;
static int regmap_ibt_read(void *context, const void *addr, size_t reg_size,
--
2.16.4