mmc: dw_mmc: fix multiple drv_data NULL dereferences

800d78bfccb3d ("mmc: dw_mmc: add support for implementation specific
callbacks") -- merged in v3.7-rc1 -- introduced multiple NULL pointer
dereferences when the default dw_mci_pltfm_probe() is used, as it sets
host->drv_data to NULL, and that's only checked against NULL in 1 out of
the 7 cases where it is dereferenced.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Acked-by: Jaehoon Chung <jh80.chung@samsung.com>
Acked-by: Will Newton <will.newton@imgtec.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

2 files changed, 19 insertions, 14 deletions

diff --git a/drivers/mmc/host/dw_mmc-pltfm.c b/drivers/mmc/host/dw_mmc-pltfm.c
index c960ca7ffbe6..e5957211b171 100644
--- a/drivers/mmc/host/dw_mmc-pltfm.c
+++ b/drivers/mmc/host/dw_mmc-pltfm.c
@@ -50,8 +50,8 @@ int dw_mci_pltfm_register(struct platform_device *pdev,
         if (!host->regs)
                 return -ENOMEM;
 
-        if (host->drv_data->init) {
-                ret = host->drv_data->init(host);
+        if (drv_data && drv_data->init) {
+                ret = drv_data->init(host);
                 if (ret)
                         return ret;
         }
diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index 4b2bedc887ba..b087f66e30c4 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -232,6 +232,7 @@ static u32 dw_mci_prepare_command(struct mmc_host *mmc, struct mmc_command *cmd)
 {
         struct mmc_data *data;
         struct dw_mci_slot *slot = mmc_priv(mmc);
+        struct dw_mci_drv_data *drv_data = slot->host->drv_data;
         u32 cmdr;
         cmd->error = -EINPROGRESS;
 
@@ -261,8 +262,8 @@ static u32 dw_mci_prepare_command(struct mmc_host *mmc, struct mmc_command *cmd)
                         cmdr |= SDMMC_CMD_DAT_WR;
         }
 
-        if (slot->host->drv_data->prepare_command)
-                slot->host->drv_data->prepare_command(slot->host, &cmdr);
+        if (drv_data && drv_data->prepare_command)
+                drv_data->prepare_command(slot->host, &cmdr);
 
         return cmdr;
 }
@@ -772,6 +773,7 @@ static void dw_mci_request(struct mmc_host *mmc, struct mmc_request *mrq)
 static void dw_mci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
 {
         struct dw_mci_slot *slot = mmc_priv(mmc);
+        struct dw_mci_drv_data *drv_data = slot->host->drv_data;
         u32 regs;
 
         /* set default 1 bit mode */
@@ -807,8 +809,8 @@ static void dw_mci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
                 slot->clock = ios->clock;
         }
 
-        if (slot->host->drv_data->set_ios)
-                slot->host->drv_data->set_ios(slot->host, ios);
+        if (drv_data && drv_data->set_ios)
+                drv_data->set_ios(slot->host, ios);
 
         switch (ios->power_mode) {
         case MMC_POWER_UP:
@@ -1815,6 +1817,7 @@ static int dw_mci_init_slot(struct dw_mci *host, unsigned int id)
 {
         struct mmc_host *mmc;
         struct dw_mci_slot *slot;
+        struct dw_mci_drv_data *drv_data = host->drv_data;
         int ctrl_id, ret;
         u8 bus_width;
 
@@ -1854,8 +1857,8 @@ static int dw_mci_init_slot(struct dw_mci *host, unsigned int id)
         } else {
                 ctrl_id = to_platform_device(host->dev)->id;
         }
-        if (host->drv_data && host->drv_data->caps)
-                mmc->caps |= host->drv_data->caps[ctrl_id];
+        if (drv_data && drv_data->caps)
+                mmc->caps |= drv_data->caps[ctrl_id];
 
         if (host->pdata->caps2)
                 mmc->caps2 = host->pdata->caps2;
@@ -1867,10 +1870,10 @@ static int dw_mci_init_slot(struct dw_mci *host, unsigned int id)
         else
                 bus_width = 1;
 
-        if (host->drv_data->setup_bus) {
+        if (drv_data && drv_data->setup_bus) {
                 struct device_node *slot_np;
                 slot_np = dw_mci_of_find_slot_node(host->dev, slot->id);
-                ret = host->drv_data->setup_bus(host, slot_np, bus_width);
+                ret = drv_data->setup_bus(host, slot_np, bus_width);
                 if (ret)
                         goto err_setup_bus;
         }
@@ -2035,6 +2038,7 @@ static struct dw_mci_board *dw_mci_parse_dt(struct dw_mci *host)
         struct dw_mci_board *pdata;
         struct device *dev = host->dev;
         struct device_node *np = dev->of_node;
+        struct dw_mci_drv_data *drv_data = host->drv_data;
         int idx, ret;
 
         pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
@@ -2062,8 +2066,8 @@ static struct dw_mci_board *dw_mci_parse_dt(struct dw_mci *host)
 
         of_property_read_u32(np, "card-detect-delay", &pdata->detect_delay_ms);
 
-        if (host->drv_data->parse_dt) {
-                ret = host->drv_data->parse_dt(host);
+        if (drv_data && drv_data->parse_dt) {
+                ret = drv_data->parse_dt(host);
                 if (ret)
                         return ERR_PTR(ret);
         }
@@ -2080,6 +2084,7 @@ static struct dw_mci_board *dw_mci_parse_dt(struct dw_mci *host)
 
 int dw_mci_probe(struct dw_mci *host)
 {
+        struct dw_mci_drv_data *drv_data = host->drv_data;
         int width, i, ret = 0;
         u32 fifo_size;
         int init_slots = 0;
@@ -2127,8 +2132,8 @@ int dw_mci_probe(struct dw_mci *host)
         else
                 host->bus_hz = clk_get_rate(host->ciu_clk);
 
-        if (host->drv_data->setup_clock) {
-                ret = host->drv_data->setup_clock(host);
+        if (drv_data && drv_data->setup_clock) {
+                ret = drv_data->setup_clock(host);
                 if (ret) {
                         dev_err(host->dev,
                                 "implementation specific clock setup failed\n");