clk: zynq: Prevent null pointer dereference caused by kmalloc failure

The kmalloc() in zynq_clk_setup() will return null if the
physical memory has run out. As a result, if we use snprintf()
to write data to the null address, the null pointer dereference
bug will happen.

This patch uses a stack variable to replace the kmalloc().

Fixes: 0ee52b157b8e ("clk: zynq: Add clock controller driver")
Suggested-by: Michal Simek <michal.simek@amd.com>
Suggested-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Link: https://lore.kernel.org/r/20240301084437.16084-1-duoming@zju.edu.cn
Acked-by: Michal Simek <michal.simek@amd.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

diff --git a/drivers/clk/zynq/clkc.c b/drivers/clk/zynq/clkc.c
index 7bdeaff2bfd68b00a25e6cd9ef4f0623a8b2cc9a..c28d3dacf0fb22c6e2586caf2201564afb56cd7b 100644 (file)
--- a/drivers/clk/zynq/clkc.c
+++ b/drivers/clk/zynq/clkc.c
@@ -42,6 +42,7 @@ static void __iomem *zynq_clkc_base;
 #define SLCR_SWDT_CLK_SEL              (zynq_clkc_base + 0x204)
 
 #define NUM_MIO_PINS   54
+#define CLK_NAME_LEN   16
 
 #define DBG_CLK_CTRL_CLKACT_TRC                BIT(0)
 #define DBG_CLK_CTRL_CPU_1XCLKACT      BIT(1)
@@ -215,7 +216,7 @@ static void __init zynq_clk_setup(struct device_node *np)
        int i;
        u32 tmp;
        int ret;
-       char *clk_name;
+       char clk_name[CLK_NAME_LEN];
        unsigned int fclk_enable = 0;
        const char *clk_output_name[clk_max];
        const char *cpu_parents[4];
@@ -426,12 +427,10 @@ static void __init zynq_clk_setup(struct device_node *np)
                        "gem1_emio_mux", CLK_SET_RATE_PARENT,
                        SLCR_GEM1_CLK_CTRL, 0, 0, &gem1clk_lock);
 
-       tmp = strlen("mio_clk_00x");
-       clk_name = kmalloc(tmp, GFP_KERNEL);
        for (i = 0; i < NUM_MIO_PINS; i++) {
                int idx;
 
-               snprintf(clk_name, tmp, "mio_clk_%2.2d", i);
+               snprintf(clk_name, CLK_NAME_LEN, "mio_clk_%2.2d", i);
                idx = of_property_match_string(np, "clock-names", clk_name);
                if (idx >= 0)
                        can_mio_mux_parents[i] = of_clk_get_parent_name(np,
@@ -439,7 +438,6 @@ static void __init zynq_clk_setup(struct device_node *np)
                else
                        can_mio_mux_parents[i] = dummy_nm;
        }
-       kfree(clk_name);
        clk_register_mux(NULL, "can_mux", periph_parents, 4,
                        CLK_SET_RATE_NO_REPARENT, SLCR_CAN_CLK_CTRL, 4, 2, 0,
                        &canclk_lock);