diff mbox series

[net-next,v2,1/2] net/iucv: Avoid explicit cpumask var allocation on stack

Message ID 20240331053441.1276826-2-dawei.li@shingroup.cn (mailing list archive)
State Accepted
Commit be4e1304419c99a164b4c0e101c7c2a756b635b9
Delegated to: Netdev Maintainers
Headers show
Series Avoid explicit cpumask var allocation on stack | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 8 this patch: 8
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers success CCed 7 of 7 maintainers
netdev/build_clang success Errors and warnings before: 8 this patch: 8
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 8 this patch: 8
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 48 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
netdev/contest success net-next-2024-04-01--00-00 (tests: 952)

Commit Message

Dawei Li March 31, 2024, 5:34 a.m. UTC
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@shingroup.cn>
---
 net/iucv/iucv.c | 26 ++++++++++++++++++--------
 1 file changed, 18 insertions(+), 8 deletions(-)

Comments

Alexandra Winter April 2, 2024, 12:41 p.m. UTC | #1
On 31.03.24 07:34, Dawei Li wrote:
> 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@shingroup.cn>
> ---

LGTM; 
Thank you Eric for the comment and solution with the 'static' keyword.
Reviewed-by: Alexandra Winter <wintera@linux.ibm.com>
diff mbox series

Patch

diff --git a/net/iucv/iucv.c b/net/iucv/iucv.c
index a4ab615ca3e3..5e37a8ceebcb 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;
 }
 
 /**