From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Thu, 7 Mar 2019 05:41:22 +0000 (+0300)
Subject: xen, cpu_hotplug: Prevent an out of bounds access
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=93501e7330aacb38e15d26aaddc1df3485acff91;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git

xen, cpu_hotplug: Prevent an out of bounds access

[ Upstream commit 201676095dda7e5b31a5e1d116d10fc22985075e ]

The "cpu" variable comes from the sscanf() so Smatch marks it as
untrusted data.  We can't pass a higher value than "nr_cpu_ids" to
cpu_possible() or it results in an out of bounds access.

Fixes: d68d82afd4c8 ("xen: implement CPU hotplugging")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/drivers/xen/cpu_hotplug.c b/drivers/xen/cpu_hotplug.c
index f4e59c445964..17054d695411 100644
--- a/drivers/xen/cpu_hotplug.c
+++ b/drivers/xen/cpu_hotplug.c
@@ -53,7 +53,7 @@ static int vcpu_online(unsigned int cpu)
 }
 static void vcpu_hotplug(unsigned int cpu)
 {
-	if (!cpu_possible(cpu))
+	if (cpu >= nr_cpu_ids || !cpu_possible(cpu))
 		return;
 
 	switch (vcpu_online(cpu)) {