[PATCH 6.1 346/451] clk: zynq: Prevent null pointer dereference caused by kmalloc failure

Sasha Levin
2024-03-24T23:17:43Z

From: Duoming Zhou <duoming@zju.edu.cn>

[ Upstream commit 7938e9ce39d6779d2f85d822cc930f73420e54a6 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/clk/zynq/clkc.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/clk/zynq/clkc.c b/drivers/clk/zynq/clkc.c
index 7bdeaff2bfd68..c28d3dacf0fb2 100644
--- 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);
--
2.43.0