Re: [PATCH] clk: zynq: Prevent null pointer dereference caused by kmalloc failure

Michal Simek
2024-02-19T13:35:16Z

On 2/14/24 08:33, Duoming Zhou wrote:
> 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.
>
> The required memory is only 11 bytes, so this patch
> adds a "__GFP_NOFAIL" flag in kmalloc in order that
> the kmalloc will never return with failure.
>
> Fixes: 0ee52b157b8e ("clk: zynq: Add clock controller driver")
> Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
> ---
> drivers/clk/zynq/clkc.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/clk/zynq/clkc.c b/drivers/clk/zynq/clkc.c
> index 7bdeaff2bfd..7621c2f0046 100644
> --- a/drivers/clk/zynq/clkc.c
> +++ b/drivers/clk/zynq/clkc.c
> @@ -427,7 +427,7 @@ static void __init zynq_clk_setup(struct device_node *np)
> SLCR_GEM1_CLK_CTRL, 0, 0, &gem1clk_lock);
>
> tmp = strlen("mio_clk_00x");
> - clk_name = kmalloc(tmp, GFP_KERNEL);
> + clk_name = kmalloc(tmp, GFP_KERNEL | __GFP_NOFAIL);
> for (i = 0; i < NUM_MIO_PINS; i++) {
> int idx;
>

Reviewed-by: Michal Simek <michal.simek@amd.com>

Thanks,
Michal