KVM: x86: Reduce refcount if single_open() fails in kvm_mmu_rmaps_stat_open()

Refcount is increased before calling single_open() in
kvm_mmu_rmaps_stat_open(), If single_open() fails, refcount should be
restored, otherwise the vm couldn't be destroyed.

Fixes: 15b9954ec9e62 ("KVM: X86: Introduce mmu_rmaps_stat per-vm debugfs file")
Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
Message-Id: <a75900413bb8b1e556be690e9588a0f92e946a30.1665733883.git.houwenlong.hwl@antgroup.com>
[Preserved return value of single_open. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/debugfs.c b/arch/x86/kvm/debugfs.c
index cfed36aba2f70c8f7b01f54ea9c494f121b81c8c..c1390357126ab4668f04087e09a039e7fbf6d987 100644 (file)
--- a/arch/x86/kvm/debugfs.c
+++ b/arch/x86/kvm/debugfs.c
@@ -158,11 +158,16 @@ out:
 static int kvm_mmu_rmaps_stat_open(struct inode *inode, struct file *file)
 {
        struct kvm *kvm = inode->i_private;
+       int r;
 
        if (!kvm_get_kvm_safe(kvm))
                return -ENOENT;
 
-       return single_open(file, kvm_mmu_rmaps_stat_show, kvm);
+       r = single_open(file, kvm_mmu_rmaps_stat_show, kvm);
+       if (r < 0)
+               kvm_put_kvm(kvm);
+
+       return r;
 }
 
 static int kvm_mmu_rmaps_stat_release(struct inode *inode, struct file *file)