linux-kernel - [PATCH v2] hv_netvsc: Replace one-element array with flexible array member

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Message-ID: <20250116211932.139564-2-thorsten.blum@linux.dev>
Date: Thu, 16 Jan 2025 22:19:32 +0100
From: Thorsten Blum <thorsten.blum@...ux.dev>
To: "K. Y. Srinivasan" <kys@...rosoft.com>,
	Haiyang Zhang <haiyangz@...rosoft.com>,
	Wei Liu <wei.liu@...nel.org>,
	Dexuan Cui <decui@...rosoft.com>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>
Cc: linux-hardening@...r.kernel.org,
	Roman Kisel <romank@...ux.microsoft.com>,
	Thorsten Blum <thorsten.blum@...ux.dev>,
	linux-hyperv@...r.kernel.org,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2] hv_netvsc: Replace one-element array with flexible array member

Replace the deprecated one-element array with a modern flexible array
member in the struct nvsp_1_message_send_receive_buffer_complete.

Use struct_size_t(,,1) instead of sizeof() to maintain the same size.

Compile-tested only.

Link: https://github.com/KSPP/linux/issues/79
Signed-off-by: Thorsten Blum <thorsten.blum@...ux.dev>
---
Changes in v2:
- Replace sizeof() with struct_size_t(,,1) to maintain the same size
  after feedback from Roman Kisel (thanks!)
- Link to v1: https://lore.kernel.org/r/20250116201635.47870-2-thorsten.blum@linux.dev/
---
 drivers/net/hyperv/hyperv_net.h | 2 +-
 drivers/net/hyperv/netvsc.c     | 3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
index e690b95b1bbb..234db693cefa 100644
--- a/drivers/net/hyperv/hyperv_net.h
+++ b/drivers/net/hyperv/hyperv_net.h
@@ -464,7 +464,7 @@ struct nvsp_1_message_send_receive_buffer_complete {
 	 *  LargeOffset                            SmallOffset
 	 */
 
-	struct nvsp_1_receive_buffer_section sections[1];
+	struct nvsp_1_receive_buffer_section sections[];
 } __packed;
 
 /*
diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index 9afb08dbc350..d6f5b9ea3109 100644
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -866,7 +866,8 @@ static void netvsc_send_completion(struct net_device *ndev,
 
 	case NVSP_MSG1_TYPE_SEND_RECV_BUF_COMPLETE:
 		if (msglen < sizeof(struct nvsp_message_header) +
-				sizeof(struct nvsp_1_message_send_receive_buffer_complete)) {
+				struct_size_t(struct nvsp_1_message_send_receive_buffer_complete,
+					      sections, 1)) {
 			netdev_err(ndev, "nvsp_msg1 length too small: %u\n",
 				   msglen);
 			return;
-- 
2.48.0