From c920a191302e3a4b3a98aeabce37d715fdf5cea5 Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Wed, 12 Feb 2020 13:30:19 -0600 Subject: Bluetooth: hci_uart: Replace zero-length array with flexible-array member 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 Signed-off-by: Marcel Holtmann --- drivers/bluetooth/hci_ag6xx.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/bluetooth') diff --git a/drivers/bluetooth/hci_ag6xx.c b/drivers/bluetooth/hci_ag6xx.c index 8bafa650b5b0..1f55df93e4ce 100644 --- a/drivers/bluetooth/hci_ag6xx.c +++ b/drivers/bluetooth/hci_ag6xx.c @@ -27,7 +27,7 @@ struct ag6xx_data { struct pbn_entry { __le32 addr; __le32 plen; - __u8 data[0]; + __u8 data[]; } __packed; static int ag6xx_open(struct hci_uart *hu) -- cgit v1.2.3