mmc: dw_mmc: Fix out-of-bounds access for slot's caps

Add num_caps field for dw_mci_drv_data to validate the controller
id from DT alias and non-DT ways.
Reported-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Fixes: 800d78bf ("mmc: dw_mmc: add support for implementation specific callbacks")
Cc: <stable@vger.kernel.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/dw_mmc-exynos.c

@@ -487,6 +487,7 @@ static unsigned long exynos_dwmmc_caps[4] = {
 
 static const struct dw_mci_drv_data exynos_drv_data = {
 	.caps			= exynos_dwmmc_caps,
+	.num_caps		= ARRAY_SIZE(exynos_dwmmc_caps),
 	.init			= dw_mci_exynos_priv_init,
 	.set_ios		= dw_mci_exynos_set_ios,
 	.parse_dt		= dw_mci_exynos_parse_dt,

drivers/mmc/host/dw_mmc-k3.c

@@ -210,6 +210,7 @@ static int dw_mci_hi6220_execute_tuning(struct dw_mci_slot *slot, u32 opcode)
 
 static const struct dw_mci_drv_data hi6220_data = {
 	.caps			= dw_mci_hi6220_caps,
+	.num_caps		= ARRAY_SIZE(dw_mci_hi6220_caps),
 	.switch_voltage		= dw_mci_hi6220_switch_voltage,
 	.set_ios		= dw_mci_hi6220_set_ios,
 	.parse_dt		= dw_mci_hi6220_parse_dt,

drivers/mmc/host/dw_mmc-rockchip.c

@@ -319,6 +319,7 @@ static const struct dw_mci_drv_data rk2928_drv_data = {
 
 static const struct dw_mci_drv_data rk3288_drv_data = {
 	.caps			= dw_mci_rk3288_dwmmc_caps,
+	.num_caps		= ARRAY_SIZE(dw_mci_rk3288_dwmmc_caps),
 	.set_ios		= dw_mci_rk3288_set_ios,
 	.execute_tuning		= dw_mci_rk3288_execute_tuning,
 	.parse_dt		= dw_mci_rk3288_parse_dt,

drivers/mmc/host/dw_mmc-zx.c

@@ -195,6 +195,7 @@ static unsigned long zx_dwmmc_caps[3] = {
 
 static const struct dw_mci_drv_data zx_drv_data = {
 	.caps			= zx_dwmmc_caps,
+	.num_caps		= ARRAY_SIZE(zx_dwmmc_caps),
 	.execute_tuning		= dw_mci_zx_execute_tuning,
 	.prepare_hs400_tuning	= dw_mci_zx_prepare_hs400_tuning,
 	.parse_dt               = dw_mci_zx_parse_dt,

drivers/mmc/host/dw_mmc.c

@@ -2804,8 +2804,15 @@ static int dw_mci_init_slot_caps(struct dw_mci_slot *slot)
 	} else {
 		ctrl_id = to_platform_device(host->dev)->id;
 	}
-	if (drv_data && drv_data->caps)
+
+	if (drv_data && drv_data->caps) {
+		if (ctrl_id >= drv_data->num_caps) {
+			dev_err(host->dev, "invalid controller id %d\n",
+				ctrl_id);
+			return -EINVAL;
+		}
 		mmc->caps |= drv_data->caps[ctrl_id];
+	}
 
 	if (host->pdata->caps2)
 		mmc->caps2 = host->pdata->caps2;

drivers/mmc/host/dw_mmc.h

@@ -543,6 +543,7 @@ struct dw_mci_slot {
 /**
  * dw_mci driver data - dw-mshc implementation specific driver data.
  * @caps: mmc subsystem specified capabilities of the controller(s).
+ * @num_caps: number of capabilities specified by @caps.
  * @init: early implementation specific initialization.
  * @set_ios: handle bus specific extensions.
  * @parse_dt: parse implementation specific device tree properties.
@@ -554,6 +555,7 @@ struct dw_mci_slot {
  */
 struct dw_mci_drv_data {
 	unsigned long	*caps;
+	u32		num_caps;
 	int		(*init)(struct dw_mci *host);
 	void		(*set_ios)(struct dw_mci *host, struct mmc_ios *ios);
 	int		(*parse_dt)(struct dw_mci *host);