soc: aspeed: lpc-snoop: Constrain parameters in channel paths

Ensure pointers and the channel index are valid before use.

Link: https://patch.msgid.link/20250616-aspeed-lpc-snoop-fixes-v2-4-3cdd59c934d3@codeconstruct.com.au
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>

diff --git a/drivers/soc/aspeed/aspeed-lpc-snoop.c b/drivers/soc/aspeed/aspeed-lpc-snoop.c
index ca7536213e0986f737606a52996ffea620df2a7a..804c6ed9c4c671da73a6c66c1de41c59922c82dc 100644 (file)
--- a/drivers/soc/aspeed/aspeed-lpc-snoop.c
+++ b/drivers/soc/aspeed/aspeed-lpc-snoop.c
@@ -25,7 +25,6 @@
 
 #define DEVICE_NAME    "aspeed-lpc-snoop"
 
-#define NUM_SNOOP_CHANNELS 2
 #define SNOOP_FIFO_SIZE 2048
 
 #define HICR5  0x80
@@ -57,6 +56,12 @@ struct aspeed_lpc_snoop_model_data {
        unsigned int has_hicrb_ensnp;
 };
 
+enum aspeed_lpc_snoop_index {
+       ASPEED_LPC_SNOOP_INDEX_0 = 0,
+       ASPEED_LPC_SNOOP_INDEX_1 = 1,
+       ASPEED_LPC_SNOOP_INDEX_MAX = ASPEED_LPC_SNOOP_INDEX_1,
+};
+
 struct aspeed_lpc_snoop_channel {
        bool enabled;
        struct kfifo            fifo;
@@ -68,7 +73,7 @@ struct aspeed_lpc_snoop {
        struct regmap           *regmap;
        int                     irq;
        struct clk              *clk;
-       struct aspeed_lpc_snoop_channel chan[NUM_SNOOP_CHANNELS];
+       struct aspeed_lpc_snoop_channel chan[ASPEED_LPC_SNOOP_INDEX_MAX + 1];
 };
 
 static struct aspeed_lpc_snoop_channel *snoop_file_to_chan(struct file *file)
@@ -182,9 +187,10 @@ static int aspeed_lpc_snoop_config_irq(struct aspeed_lpc_snoop *lpc_snoop,
        return 0;
 }
 
+__attribute__((nonnull))
 static int aspeed_lpc_enable_snoop(struct aspeed_lpc_snoop *lpc_snoop,
                                   struct device *dev,
-                                  int channel, u16 lpc_port)
+                                  enum aspeed_lpc_snoop_index channel, u16 lpc_port)
 {
        const struct aspeed_lpc_snoop_model_data *model_data;
        u32 hicr5_en, snpwadr_mask, snpwadr_shift, hicrb_en;
@@ -251,8 +257,9 @@ err_free_fifo:
        return rc;
 }
 
+__attribute__((nonnull))
 static void aspeed_lpc_disable_snoop(struct aspeed_lpc_snoop *lpc_snoop,
-                                    int channel)
+                                    enum aspeed_lpc_snoop_index channel)
 {
        if (!lpc_snoop->chan[channel].enabled)
                return;
@@ -331,16 +338,16 @@ static int aspeed_lpc_snoop_probe(struct platform_device *pdev)
        if (rc)
                goto err;
 
-       rc = aspeed_lpc_enable_snoop(lpc_snoop, dev, 0, port);
+       rc = aspeed_lpc_enable_snoop(lpc_snoop, dev, ASPEED_LPC_SNOOP_INDEX_0, port);
        if (rc)
                goto err;
 
        /* Configuration of 2nd snoop channel port is optional */
        if (of_property_read_u32_index(dev->of_node, "snoop-ports",
                                       1, &port) == 0) {
-               rc = aspeed_lpc_enable_snoop(lpc_snoop, dev, 1, port);
+               rc = aspeed_lpc_enable_snoop(lpc_snoop, dev, ASPEED_LPC_SNOOP_INDEX_1, port);
                if (rc) {
-                       aspeed_lpc_disable_snoop(lpc_snoop, 0);
+                       aspeed_lpc_disable_snoop(lpc_snoop, ASPEED_LPC_SNOOP_INDEX_0);
                        goto err;
                }
        }
@@ -358,8 +365,8 @@ static void aspeed_lpc_snoop_remove(struct platform_device *pdev)
        struct aspeed_lpc_snoop *lpc_snoop = dev_get_drvdata(&pdev->dev);
 
        /* Disable both snoop channels */
-       aspeed_lpc_disable_snoop(lpc_snoop, 0);
-       aspeed_lpc_disable_snoop(lpc_snoop, 1);
+       aspeed_lpc_disable_snoop(lpc_snoop, ASPEED_LPC_SNOOP_INDEX_0);
+       aspeed_lpc_disable_snoop(lpc_snoop, ASPEED_LPC_SNOOP_INDEX_1);
 
        clk_disable_unprepare(lpc_snoop->clk);
 }