[PATCH] [v4] myri10ge: avoid uninitialized variable use

[Arnd Bergmann <arnd@kernel.org>]

From: Arnd Bergmann <arnd@arndb.de>

While compile testing on less common architectures, I noticed that gcc-10 on
s390 finds a bug that all other configurations seem to miss:

drivers/net/ethernet/myricom/myri10ge/myri10ge.c: In function 'myri10ge_set_multicast_list':
drivers/net/ethernet/myricom/myri10ge/myri10ge.c:391:25: error: 'cmd.data0' is used uninitialized in this function [-Werror=uninitialized]
  391 |  buf->data0 = htonl(data->data0);
      |                         ^~
drivers/net/ethernet/myricom/myri10ge/myri10ge.c:392:25: error: '*((void *)&cmd+4)' is used uninitialized in this function [-Werror=uninitialized]
  392 |  buf->data1 = htonl(data->data1);
      |                         ^~
drivers/net/ethernet/myricom/myri10ge/myri10ge.c: In function 'myri10ge_allocate_rings':
drivers/net/ethernet/myricom/myri10ge/myri10ge.c:392:13: error: 'cmd.data1' is used uninitialized in this function [-Werror=uninitialized]
  392 |  buf->data1 = htonl(data->data1);
drivers/net/ethernet/myricom/myri10ge/myri10ge.c:1939:22: note: 'cmd.data1' was declared here
 1939 |  struct myri10ge_cmd cmd;
      |                      ^~~
drivers/net/ethernet/myricom/myri10ge/myri10ge.c:393:13: error: 'cmd.data2' is used uninitialized in this function [-Werror=uninitialized]
  393 |  buf->data2 = htonl(data->data2);
drivers/net/ethernet/myricom/myri10ge/myri10ge.c:1939:22: note: 'cmd.data2' was declared here
 1939 |  struct myri10ge_cmd cmd;

It would be nice to understand how to make other compilers catch this as
well, but for the moment I'll just shut up the warning by fixing the
undefined behavior in this driver.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
v2..v4: address more instances of the same bug
---
 .../net/ethernet/myricom/myri10ge/myri10ge.c  | 28 ++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/myricom/myri10ge/myri10ge.c b/drivers/net/ethernet/myricom/myri10ge/myri10ge.c
index cea28aa971cc..25b46d8c49e6 100644
--- a/drivers/net/ethernet/myricom/myri10ge/myri10ge.c
+++ b/drivers/net/ethernet/myricom/myri10ge/myri10ge.c
@@ -688,6 +688,9 @@ static int myri10ge_get_firmware_capabilities(struct myri10ge_priv *mgp)
 
 	/* probe for IPv6 TSO support */
 	mgp->features = NETIF_F_SG | NETIF_F_HW_CSUM | NETIF_F_TSO;
+	cmd.data0 = 0,
+	cmd.data1 = 0,
+	cmd.data2 = 0,
 	status = myri10ge_send_cmd(mgp, MXGEFW_CMD_GET_MAX_TSO6_HDR_SIZE,
 				   &cmd, 0);
 	if (status == 0) {
@@ -806,6 +809,7 @@ static int myri10ge_update_mac_address(struct myri10ge_priv *mgp,
 		     | (addr[2] << 8) | addr[3]);
 
 	cmd.data1 = ((addr[4] << 8) | (addr[5]));
+	cmd.data2 = 0;
 
 	status = myri10ge_send_cmd(mgp, MXGEFW_SET_MAC_ADDRESS, &cmd, 0);
 	return status;
@@ -817,6 +821,9 @@ static int myri10ge_change_pause(struct myri10ge_priv *mgp, int pause)
 	int status, ctl;
 
 	ctl = pause ? MXGEFW_ENABLE_FLOW_CONTROL : MXGEFW_DISABLE_FLOW_CONTROL;
+	cmd.data0 = 0,
+	cmd.data1 = 0,
+	cmd.data2 = 0,
 	status = myri10ge_send_cmd(mgp, ctl, &cmd, 0);
 
 	if (status) {
@@ -834,6 +841,9 @@ myri10ge_change_promisc(struct myri10ge_priv *mgp, int promisc, int atomic)
 	int status, ctl;
 
 	ctl = promisc ? MXGEFW_ENABLE_PROMISC : MXGEFW_DISABLE_PROMISC;
+	cmd.data0 = 0;
+	cmd.data1 = 0;
+	cmd.data2 = 0;
 	status = myri10ge_send_cmd(mgp, ctl, &cmd, atomic);
 	if (status)
 		netdev_err(mgp->dev, "Failed to set promisc mode\n");
@@ -1946,6 +1956,8 @@ static int myri10ge_allocate_rings(struct myri10ge_slice_state *ss)
 	/* get ring sizes */
 	slice = ss - mgp->ss;
 	cmd.data0 = slice;
+	cmd.data1 = 0;
+	cmd.data2 = 0;
 	status = myri10ge_send_cmd(mgp, MXGEFW_CMD_GET_SEND_RING_SIZE, &cmd, 0);
 	tx_ring_size = cmd.data0;
 	cmd.data0 = slice;
@@ -2238,12 +2250,16 @@ static int myri10ge_get_txrx(struct myri10ge_priv *mgp, int slice)
 	status = 0;
 	if (slice == 0 || (mgp->dev->real_num_tx_queues > 1)) {
 		cmd.data0 = slice;
+		cmd.data1 = 0;
+		cmd.data2 = 0;
 		status = myri10ge_send_cmd(mgp, MXGEFW_CMD_GET_SEND_OFFSET,
 					   &cmd, 0);
 		ss->tx.lanai = (struct mcp_kreq_ether_send __iomem *)
 		    (mgp->sram + cmd.data0);
 	}
 	cmd.data0 = slice;
+	cmd.data1 = 0;
+	cmd.data2 = 0;
 	status |= myri10ge_send_cmd(mgp, MXGEFW_CMD_GET_SMALL_RX_OFFSET,
 				    &cmd, 0);
 	ss->rx_small.lanai = (struct mcp_kreq_ether_recv __iomem *)
@@ -2312,6 +2328,7 @@ static int myri10ge_open(struct net_device *dev)
 	if (mgp->num_slices > 1) {
 		cmd.data0 = mgp->num_slices;
 		cmd.data1 = MXGEFW_SLICE_INTR_MODE_ONE_PER_SLICE;
+		cmd.data2 = 0;
 		if (mgp->dev->real_num_tx_queues > 1)
 			cmd.data1 |= MXGEFW_SLICE_ENABLE_MULTIPLE_TX_QUEUES;
 		status = myri10ge_send_cmd(mgp, MXGEFW_CMD_ENABLE_RSS_QUEUES,
@@ -2414,6 +2431,8 @@ static int myri10ge_open(struct net_device *dev)
 
 	/* now give firmware buffers sizes, and MTU */
 	cmd.data0 = dev->mtu + ETH_HLEN + VLAN_HLEN;
+	cmd.data1 = 0;
+	cmd.data2 = 0;
 	status = myri10ge_send_cmd(mgp, MXGEFW_CMD_SET_MTU, &cmd, 0);
 	cmd.data0 = mgp->small_bytes;
 	status |=
@@ -2472,7 +2491,6 @@ static int myri10ge_open(struct net_device *dev)
 static int myri10ge_close(struct net_device *dev)
 {
 	struct myri10ge_priv *mgp = netdev_priv(dev);
-	struct myri10ge_cmd cmd;
 	int status, old_down_cnt;
 	int i;
 
@@ -2491,8 +2509,13 @@ static int myri10ge_close(struct net_device *dev)
 
 	netif_tx_stop_all_queues(dev);
 	if (mgp->rebooted == 0) {
+		struct myri10ge_cmd cmd;
+
 		old_down_cnt = mgp->down_cnt;
 		mb();
+		cmd.data0 = 0;
+		cmd.data1 = 0;
+		cmd.data2 = 0;
 		status =
 		    myri10ge_send_cmd(mgp, MXGEFW_CMD_ETHERNET_DOWN, &cmd, 0);
 		if (status)
@@ -2956,6 +2979,9 @@ static void myri10ge_set_multicast_list(struct net_device *dev)
 
 	/* Disable multicast filtering */
 
+	cmd.data0 = 0;
+	cmd.data1 = 0;
+	cmd.data2 = 0;
 	err = myri10ge_send_cmd(mgp, MXGEFW_ENABLE_ALLMULTI, &cmd, 1);
 	if (err != 0) {
 		netdev_err(dev, "Failed MXGEFW_ENABLE_ALLMULTI, error status: %d\n",
-- 
2.39.5