Subject: [PATCH] x86/mm: Fix cpumask_of_node() error condition

From: Peter Zijlstra <[email-masked]>
Date: Tue, 3 Sep 2019 09:53:52 +0200

On Mon, Sep 02, 2019 at 08:17:31PM +0200, Ingo Molnar wrote:

> Nitpicking: please also fix the kernel message to say ">=".

Full patch below.

---
Subject: x86/mm: Fix cpumask_of_node() error condition

When CONFIG_DEBUG_PER_CPU_MAPS we validate that the @node argument of
cpumask_of_node() is a valid node_id. It however forgets to check for
negative numbers. Fix this by explicitly casting to unsigned.

  (unsigned)node >= nr_node_ids

verifies: 0 <= node < nr_node_ids

Also ammend the error message to match the condition.

Acked-by: Ingo Molnar <[email-masked]>
Signed-off-by: Peter Zijlstra (Intel) <[email-masked]>
---
 arch/x86/mm/numa.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c
index e6dad600614c..4123100e0eaf 100644
--- a/arch/x86/mm/numa.c
+++ b/arch/x86/mm/numa.c
@@ -861,9 +861,9 @@ void numa_remove_cpu(int cpu)
  */
 const struct cpumask *cpumask_of_node(int node)
 {
-	if (node >= nr_node_ids) {
+	if ((unsigned)node >= nr_node_ids) {
 		printk(KERN_WARNING
-			"cpumask_of_node(%d): node > nr_node_ids(%u)\n",
+			"cpumask_of_node(%d): (unsigned)node >= nr_node_ids(%u)\n",
 			node, nr_node_ids);
 		dump_stack();
 		return cpu_none_mask;