[PATCH][next] staging: gdm724x: Replace one-element array with flexible-array member

[PATCH][next] staging: gdm724x: Replace one-element array with flexible-array member

[Gustavo A. R. Silva]

There is a regular need in the kernel to provide a way to declare having
a dynamically sized set of trailing elements in a structure. Kernel code
should always use “flexible array members”[1] for these cases. The older
style of one-element or zero-length arrays should no longer be used[2].

This helps with the ongoing efforts to globally enable -Warray-bounds
and get us closer to being able to tighten the FORTIFY_SOURCE routines
on memcpy().

This issue was found with the help of Coccinelle and audited and fixed,
manually.

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.16/process/deprecated.html#zero-length-and-one-element-arrays

Link: https://github.com/KSPP/linux/issues/79
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
 drivers/staging/gdm724x/hci_packet.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/gdm724x/hci_packet.h b/drivers/staging/gdm724x/hci_packet.h
index faecdfbc664f..3bb01e94f3b5 100644
--- a/drivers/staging/gdm724x/hci_packet.h
+++ b/drivers/staging/gdm724x/hci_packet.h
@@ -34,7 +34,7 @@ struct hci_packet {
 struct tlv {
 	u8 type;
 	u8 len;
-	u8 *data[1];
+	u8 *data[];
 } __packed;
 
 struct sdu_header {
-- 
2.27.0

Re: [PATCH][next] staging: gdm724x: Replace one-element array with flexible-array member

[Dan Carpenter]

On Fri, Feb 04, 2022 at 05:29:44PM -0600, Gustavo A. R. Silva wrote:
> There is a regular need in the kernel to provide a way to declare having
> a dynamically sized set of trailing elements in a structure. Kernel code
> should always use “flexible array members”[1] for these cases. The older
> style of one-element or zero-length arrays should no longer be used[2].
> 
> This helps with the ongoing efforts to globally enable -Warray-bounds
> and get us closer to being able to tighten the FORTIFY_SOURCE routines
> on memcpy().
> 
> This issue was found with the help of Coccinelle and audited and fixed,
> manually.
> 
> [1] https://en.wikipedia.org/wiki/Flexible_array_member
> [2] https://www.kernel.org/doc/html/v5.16/process/deprecated.html#zero-length-and-one-element-arrays
> 
> Link: https://github.com/KSPP/linux/issues/79
> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>

regards,
dan carpenter