scsi: megaraid: Avoid mismatched storage type sizes

Remove needless use of mbox_t, replacing with just struct
mbox_out. Silences compiler warnings under a -Warray-bounds build:

drivers/scsi/megaraid.c: In function 'megaraid_probe_one':
drivers/scsi/megaraid.c:3615:30: error: array subscript 'mbox_t[0]' is partly outside array bounds of 'unsigned char[15]' [-Werror=array-bounds]
 3615 |         mbox->m_out.xferaddr = (u32)adapter->buf_dma_handle;
      |         ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/scsi/megaraid.c:3599:23: note: while referencing 'raw_mbox'
 3599 |         unsigned char raw_mbox[sizeof(struct mbox_out)];
      |                       ^~~~~~~~

Link: https://lore.kernel.org/r/20220105173633.2421129-1-keescook@chromium.org
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Sumit Saxena <sumit.saxena@broadcom.com>
Cc: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Cc: "James E.J. Bottomley" <jejb@linux.ibm.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: megaraidlinux.pdl@broadcom.com
Cc: linux-scsi@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/megaraid.c

@@ -192,23 +192,21 @@ mega_query_adapter(adapter_t *adapter)
 {
 	dma_addr_t	prod_info_dma_handle;
 	mega_inquiry3	*inquiry3;
-	u8	raw_mbox[sizeof(struct mbox_out)];
-	mbox_t	*mbox;
+	struct mbox_out	mbox;
+	u8	*raw_mbox = (u8 *)&mbox;
 	int	retval;
 
 	/* Initialize adapter inquiry mailbox */
 
-	mbox = (mbox_t *)raw_mbox;
-
 	memset((void *)adapter->mega_buffer, 0, MEGA_BUFFER_SIZE);
-	memset(&mbox->m_out, 0, sizeof(raw_mbox));
+	memset(&mbox, 0, sizeof(mbox));
 
 	/*
 	 * Try to issue Inquiry3 command
 	 * if not succeeded, then issue MEGA_MBOXCMD_ADAPTERINQ command and
 	 * update enquiry3 structure
 	 */
-	mbox->m_out.xferaddr = (u32)adapter->buf_dma_handle;
+	mbox.xferaddr = (u32)adapter->buf_dma_handle;
 
 	inquiry3 = (mega_inquiry3 *)adapter->mega_buffer;
 
@@ -232,10 +230,10 @@ mega_query_adapter(adapter_t *adapter)
 
 		inq = &ext_inq->raid_inq;
 
-		mbox->m_out.xferaddr = (u32)dma_handle;
+		mbox.xferaddr = (u32)dma_handle;
 
 		/*issue old 0x04 command to adapter */
-		mbox->m_out.cmd = MEGA_MBOXCMD_ADPEXTINQ;
+		mbox.cmd = MEGA_MBOXCMD_ADPEXTINQ;
 
 		issue_scb_block(adapter, raw_mbox);
 
@@ -262,7 +260,7 @@ mega_query_adapter(adapter_t *adapter)
 						      sizeof(mega_product_info),
 						      DMA_FROM_DEVICE);
 
-		mbox->m_out.xferaddr = prod_info_dma_handle;
+		mbox.xferaddr = prod_info_dma_handle;
 
 		raw_mbox[0] = FC_NEW_CONFIG;	/* i.e. mbox->cmd=0xA1 */
 		raw_mbox[2] = NC_SUBOP_PRODUCT_INFO;	/* i.e. 0x0E */
@@ -3569,16 +3567,14 @@ mega_n_to_m(void __user *arg, megacmd_t *mc)
 static int
 mega_is_bios_enabled(adapter_t *adapter)
 {
-	unsigned char	raw_mbox[sizeof(struct mbox_out)];
-	mbox_t	*mbox;
-
-	mbox = (mbox_t *)raw_mbox;
+	struct mbox_out mbox;
+	unsigned char	*raw_mbox = (u8 *)&mbox;
 
-	memset(&mbox->m_out, 0, sizeof(raw_mbox));
+	memset(&mbox, 0, sizeof(mbox));
 
 	memset((void *)adapter->mega_buffer, 0, MEGA_BUFFER_SIZE);
 
-	mbox->m_out.xferaddr = (u32)adapter->buf_dma_handle;
+	mbox.xferaddr = (u32)adapter->buf_dma_handle;
 
 	raw_mbox[0] = IS_BIOS_ENABLED;
 	raw_mbox[2] = GET_BIOS;
@@ -3600,13 +3596,11 @@ mega_is_bios_enabled(adapter_t *adapter)
 static void
 mega_enum_raid_scsi(adapter_t *adapter)
 {
-	unsigned char raw_mbox[sizeof(struct mbox_out)];
-	mbox_t *mbox;
+	struct mbox_out mbox;
+	unsigned char	*raw_mbox = (u8 *)&mbox;
 	int i;
 
-	mbox = (mbox_t *)raw_mbox;
-
-	memset(&mbox->m_out, 0, sizeof(raw_mbox));
+	memset(&mbox, 0, sizeof(mbox));
 
 	/*
 	 * issue command to find out what channels are raid/scsi
@@ -3616,7 +3610,7 @@ mega_enum_raid_scsi(adapter_t *adapter)
 
 	memset((void *)adapter->mega_buffer, 0, MEGA_BUFFER_SIZE);
 
-	mbox->m_out.xferaddr = (u32)adapter->buf_dma_handle;
+	mbox.xferaddr = (u32)adapter->buf_dma_handle;
 
 	/*
 	 * Non-ROMB firmware fail this command, so all channels
@@ -3655,23 +3649,21 @@ static void
 mega_get_boot_drv(adapter_t *adapter)
 {
 	struct private_bios_data	*prv_bios_data;
-	unsigned char	raw_mbox[sizeof(struct mbox_out)];
-	mbox_t	*mbox;
+	struct mbox_out mbox;
+	unsigned char	*raw_mbox = (u8 *)&mbox;
 	u16	cksum = 0;
 	u8	*cksum_p;
 	u8	boot_pdrv;
 	int	i;
 
-	mbox = (mbox_t *)raw_mbox;
-
-	memset(&mbox->m_out, 0, sizeof(raw_mbox));
+	memset(&mbox, 0, sizeof(mbox));
 
 	raw_mbox[0] = BIOS_PVT_DATA;
 	raw_mbox[2] = GET_BIOS_PVT_DATA;
 
 	memset((void *)adapter->mega_buffer, 0, MEGA_BUFFER_SIZE);
 
-	mbox->m_out.xferaddr = (u32)adapter->buf_dma_handle;
+	mbox.xferaddr = (u32)adapter->buf_dma_handle;
 
 	adapter->boot_ldrv_enabled = 0;
 	adapter->boot_ldrv = 0;
@@ -3721,13 +3713,11 @@ mega_get_boot_drv(adapter_t *adapter)
 static int
 mega_support_random_del(adapter_t *adapter)
 {
-	unsigned char raw_mbox[sizeof(struct mbox_out)];
-	mbox_t *mbox;
+	struct mbox_out mbox;
+	unsigned char	*raw_mbox = (u8 *)&mbox;
 	int rval;
 
-	mbox = (mbox_t *)raw_mbox;
-
-	memset(&mbox->m_out, 0, sizeof(raw_mbox));
+	memset(&mbox, 0, sizeof(mbox));
 
 	/*
 	 * issue command
@@ -3750,13 +3740,11 @@ mega_support_random_del(adapter_t *adapter)
 static int
 mega_support_ext_cdb(adapter_t *adapter)
 {
-	unsigned char raw_mbox[sizeof(struct mbox_out)];
-	mbox_t *mbox;
+	struct mbox_out mbox;
+	unsigned char	*raw_mbox = (u8 *)&mbox;
 	int rval;
 
-	mbox = (mbox_t *)raw_mbox;
-
-	memset(&mbox->m_out, 0, sizeof(raw_mbox));
+	memset(&mbox, 0, sizeof(mbox));
 	/*
 	 * issue command to find out if controller supports extended CDBs.
 	 */
@@ -3865,16 +3853,14 @@ mega_do_del_logdrv(adapter_t *adapter, int logdrv)
 static void
 mega_get_max_sgl(adapter_t *adapter)
 {
-	unsigned char	raw_mbox[sizeof(struct mbox_out)];
-	mbox_t	*mbox;
+	struct mbox_out	mbox;
+	unsigned char	*raw_mbox = (u8 *)&mbox;
 
-	mbox = (mbox_t *)raw_mbox;
-
-	memset(mbox, 0, sizeof(raw_mbox));
+	memset(&mbox, 0, sizeof(mbox));
 
 	memset((void *)adapter->mega_buffer, 0, MEGA_BUFFER_SIZE);
 
-	mbox->m_out.xferaddr = (u32)adapter->buf_dma_handle;
+	mbox.xferaddr = (u32)adapter->buf_dma_handle;
 
 	raw_mbox[0] = MAIN_MISC_OPCODE;
 	raw_mbox[2] = GET_MAX_SG_SUPPORT;
@@ -3888,7 +3874,7 @@ mega_get_max_sgl(adapter_t *adapter)
 	}
 	else {
 		adapter->sglen = *((char *)adapter->mega_buffer);
-		
+
 		/*
 		 * Make sure this is not more than the resources we are
 		 * planning to allocate
@@ -3910,16 +3896,14 @@ mega_get_max_sgl(adapter_t *adapter)
 static int
 mega_support_cluster(adapter_t *adapter)
 {
-	unsigned char	raw_mbox[sizeof(struct mbox_out)];
-	mbox_t	*mbox;
-
-	mbox = (mbox_t *)raw_mbox;
+	struct mbox_out	mbox;
+	unsigned char	*raw_mbox = (u8 *)&mbox;
 
-	memset(mbox, 0, sizeof(raw_mbox));
+	memset(&mbox, 0, sizeof(mbox));
 
 	memset((void *)adapter->mega_buffer, 0, MEGA_BUFFER_SIZE);
 
-	mbox->m_out.xferaddr = (u32)adapter->buf_dma_handle;
+	mbox.xferaddr = (u32)adapter->buf_dma_handle;
 
 	/*
 	 * Try to get the initiator id. This command will succeed iff the