From: Yi Xie <xieyi@kylinos.cn>
Date: Thu, 9 Jul 2026 02:19:47 +0000 (+0800)
Subject: mshv_vtl: bounds-check cpu index in vtl mmap fault handler
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=22dfdc17ceadd2783a609947af621a7f697b7765;p=thirdparty%2Flinux.git

mshv_vtl: bounds-check cpu index in vtl mmap fault handler

cpu is taken from pgoff & 0xffff.  cpu_online() does not reject cpu >=
nr_cpu_ids, and per_cpu_ptr() can then walk off __per_cpu_offset.

Signed-off-by: Yi Xie <xieyi@kylinos.cn>
Reviewed-by: Naman Jain <namjain@linux.microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
---

diff --git a/drivers/hv/mshv_vtl_main.c b/drivers/hv/mshv_vtl_main.c
index 5ba1efb3b4e7..6e3c11c68171 100644
--- a/drivers/hv/mshv_vtl_main.c
+++ b/drivers/hv/mshv_vtl_main.c
@@ -802,7 +802,7 @@ static vm_fault_t mshv_vtl_fault(struct vm_fault *vmf)
 	int cpu = vmf->pgoff & MSHV_PG_OFF_CPU_MASK;
 	int real_off = vmf->pgoff >> MSHV_REAL_OFF_SHIFT;
 
-	if (!cpu_online(cpu))
+	if (cpu >= nr_cpu_ids || !cpu_online(cpu))
 		return VM_FAULT_SIGBUS;
 	/*
 	 * CPU Hotplug is not supported in VTL2 in OpenHCL, where this kernel driver exists.