Commit be4e1304 authored by Dawei Li's avatar Dawei Li Committed by Jakub Kicinski
Browse files

net/iucv: Avoid explicit cpumask var allocation on stack 



For CONFIG_CPUMASK_OFFSTACK=y kernel, explicit allocation of cpumask
variable on stack is not recommended since it can cause potential stack
overflow.

Instead, kernel code should always use *cpumask_var API(s) to allocate
cpumask var in config-neutral way, leaving allocation strategy to
CONFIG_CPUMASK_OFFSTACK.

Use *cpumask_var API(s) to address it.

Signed-off-by: default avatarDawei Li <dawei.li@shingroup.cn>
Reviewed-by: default avatarAlexandra Winter <wintera@linux.ibm.com>
Link: https://lore.kernel.org/r/20240331053441.1276826-2-dawei.li@shingroup.cn


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent ad6afdfc

net/iucv/iucv.c

+18 −8
Original line number Diff line number Diff line
@@ -520,7 +520,7 @@ static void iucv_setmask_mp(void) 
 */

static void iucv_setmask_up(void)

{

	cpumask_t cpumask;

	static cpumask_t cpumask;

	int cpu;



	/* Disable all cpu but the first in cpu_irq_cpumask. */
@@ -628,23 +628,33 @@ static int iucv_cpu_online(unsigned int cpu) 


static int iucv_cpu_down_prep(unsigned int cpu)

{

	cpumask_t cpumask;

	cpumask_var_t cpumask;

	int ret = 0;



	if (!iucv_path_table)

		return 0;



	cpumask_copy(&cpumask, &iucv_buffer_cpumask);

	cpumask_clear_cpu(cpu, &cpumask);

	if (cpumask_empty(&cpumask))

	if (!alloc_cpumask_var(&cpumask, GFP_KERNEL))

		return -ENOMEM;



	cpumask_copy(cpumask, &iucv_buffer_cpumask);

	cpumask_clear_cpu(cpu, cpumask);

	if (cpumask_empty(cpumask)) {

		/* Can't offline last IUCV enabled cpu. */

		return -EINVAL;

		ret = -EINVAL;

		goto __free_cpumask;

	}



	iucv_retrieve_cpu(NULL);

	if (!cpumask_empty(&iucv_irq_cpumask))

		return 0;

		goto __free_cpumask;



	smp_call_function_single(cpumask_first(&iucv_buffer_cpumask),

				 iucv_allow_cpu, NULL, 1);

	return 0;



__free_cpumask:

	free_cpumask_var(cpumask);

	return ret;

}



/**