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Subject[PATCH] KVM: Fix OOM vulnerability caused by continuously creating devices
Date
From: ZhaoQiang <zhao.qiang11@zte.com.cn>

When processing the ioctl request for creating a device in the
kvm_vm_ioctl()function,the branch did not reclaim the successfully
created device,which caused memory leak.

Signed-off-by: ZhaoQiang <zhao.qiang11@zte.com.cn>
Signed-off-by: Yi Wang <wang.yi59@zte.com.cn>
---
virt/kvm/kvm_main.c | 39 ++++++++++++++++++++++++++++++++++++++-
1 file changed, 38 insertions(+), 1 deletion(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 72c4e6b39389..f4fbc935faea 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -52,6 +52,7 @@
#include <linux/lockdep.h>
#include <linux/kthread.h>
#include <linux/suspend.h>
+#include <linux/syscalls.h>

#include <asm/processor.h>
#include <asm/ioctl.h>
@@ -4092,6 +4093,40 @@ static int kvm_ioctl_create_device(struct kvm *kvm,
return 0;
}

+static int kvm_ioctl_destroy_device(struct kvm *kvm,
+ struct kvm_create_device *cd)
+{
+ struct kvm_device_ops *ops = NULL;
+ struct kvm_device *dev;
+ struct file *file;
+ int type;
+
+ if (cd->type >= ARRAY_SIZE(kvm_device_ops_table))
+ return -ENODEV;
+
+ type = array_index_nospec(cd->type, ARRAY_SIZE(kvm_device_ops_table));
+ ops = kvm_device_ops_table[type];
+ if (ops == NULL)
+ return -ENODEV;
+
+ file = fget(cd->fd);
+ if (!file)
+ return -ENODEV;
+
+ dev = file->private_data;
+ if (!dev)
+ return -ENODEV;
+
+ kvm_put_kvm(kvm);
+ mutex_lock(&kvm->lock);
+ list_del(&device->vm_node);
+ mutex_unlock(&kvm->lock);
+ ops->destroy(dev);
+ ksys_close(cd->fd);
+
+ return 0;
+}
+
static long kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg)
{
switch (arg) {
@@ -4448,8 +4483,10 @@ static long kvm_vm_ioctl(struct file *filp,
goto out;

r = -EFAULT;
- if (copy_to_user(argp, &cd, sizeof(cd)))
+ if (copy_to_user(argp, &cd, sizeof(cd))) {
+ kvm_ioctl_destroy_device(kvm, &cd);
goto out;
+ }

r = 0;
break;
--
2.27.0
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