This is a note to let you know that I've just added the patch titled
net/iucv: Avoid explicit cpumask var allocation on stack
to the 6.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
net-iucv-avoid-explicit-cpumask-var-allocation-on-st.patch
and it can be found in the queue-6.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 0c92ad72dec5df02ab660cf8588e655a4871e296
Author: Dawei Li <dawei.li@xxxxxxxxxxxx>
Date: Sun Mar 31 13:34:40 2024 +0800
net/iucv: Avoid explicit cpumask var allocation on stack
[ Upstream commit be4e1304419c99a164b4c0e101c7c2a756b635b9 ]
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: Dawei Li <dawei.li@xxxxxxxxxxxx>
Reviewed-by: Alexandra Winter <wintera@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20240331053441.1276826-2-dawei.li@xxxxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/iucv/iucv.c b/net/iucv/iucv.c
index a4ab615ca3e3e..5e37a8ceebcb8 100644
--- a/net/iucv/iucv.c
+++ b/net/iucv/iucv.c
@@ -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;
}
/**
