[PATCH][next] Bluetooth: HCI: Replace zero-length arrays with flexible-array members

[PATCH][next] Bluetooth: HCI: Replace zero-length arrays with flexible-array members

[Gustavo A. R. Silva]

Zero-length arrays are deprecated[1] and we are moving towards
adopting C99 flexible-array members instead. So, replace zero-length
arrays in a couple of structures with flex-array members.

This helps with the ongoing efforts to tighten the FORTIFY_SOURCE
routines on memcpy() and help us make progress towards globally
enabling -fstrict-flex-arrays=3 [2].

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays [1]
Link: https://gcc.gnu.org/pipermail/gcc-patches/2022-October/602902.html [2]
Link: https://github.com/KSPP/linux/issues/78
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
 include/net/bluetooth/hci.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h
index 8d773b042c85..400f8a7d0c3f 100644
--- a/include/net/bluetooth/hci.h
+++ b/include/net/bluetooth/hci.h
@@ -2156,7 +2156,7 @@ struct hci_cp_le_big_create_sync {
 	__u8    mse;
 	__le16  timeout;
 	__u8    num_bis;
-	__u8    bis[0];
+	__u8    bis[];
 } __packed;
 
 #define HCI_OP_LE_BIG_TERM_SYNC			0x206c
@@ -2174,7 +2174,7 @@ struct hci_cp_le_setup_iso_path {
 	__le16  codec_vid;
 	__u8    delay[3];
 	__u8    codec_cfg_len;
-	__u8    codec_cfg[0];
+	__u8    codec_cfg[];
 } __packed;
 
 struct hci_rp_le_setup_iso_path {
-- 
2.34.1

Re: [PATCH][next] Bluetooth: HCI: Replace zero-length arrays with flexible-array members

[Kees Cook]

On Mon, Jan 09, 2023 at 07:37:52PM -0600, Gustavo A. R. Silva wrote:
> Zero-length arrays are deprecated[1] and we are moving towards
> adopting C99 flexible-array members instead. So, replace zero-length
> arrays in a couple of structures with flex-array members.
> 
> This helps with the ongoing efforts to tighten the FORTIFY_SOURCE
> routines on memcpy() and help us make progress towards globally
> enabling -fstrict-flex-arrays=3 [2].
> 
> Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays [1]
> Link: https://gcc.gnu.org/pipermail/gcc-patches/2022-October/602902.html [2]
> Link: https://github.com/KSPP/linux/issues/78
> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Reviewed-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook