CVE-2022-49568— KVM: Don't null dereference ops->destroy

KVM: Don't null dereference ops->destroy

In the Linux kernel, the following vulnerability has been resolved: KVM: Don't null dereference ops->destroy A KVM device cleanup happens in either of two callbacks: 1) destroy() which is called when the VM is being destroyed; 2) release() which is called when a device fd is closed. Most KVM devices use 1) but Book3s's interrupt controller KVM devices (XICS, XIVE, XIVE-native) use 2) as they need to close and reopen during the machine execution. The error handling in kvm_ioctl_create_device() assumes destroy() is always defined which leads to NULL dereference as discovered by Syzkaller. This adds a checks for destroy!=NULL and adds a missing release(). This is not changing kvm_destroy_devices() as devices with defined release() should have been removed from the KVM devices list by then.

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Linux kernel 安全漏洞

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于未检查destroy回调，可能导致空指针取消引用。

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