Description: KVM: NULL pointer dereference in kvm_dirty_ring_get() in virt/kvm/dirty_ring.c
References:
 https://lore.kernel.org/kvm/CAFcO6XOmoS7EacN_n6v4Txk7xL7iqRa2gABg3F7E3Naf5uG94g@mail.gmail.com/
 https://patchwork.kernel.org/project/kvm/patch/20211121125451.9489-12-dwmw2@infradead.org/
 https://bugzilla.redhat.com/show_bug.cgi?id=2031194
 https://www.openwall.com/lists/oss-security/2021/12/14/2
 https://www.openwall.com/lists/oss-security/2022/01/17/1
Notes:
 bwh> Introduced in 5.12 by commit 629b5348841a "KVM: x86/xen: update
 bwh> wallclock region".
Bugs:
upstream: released (5.17-rc1) [55749769fe608fa3f4a075e42e89d237c8e37637]
5.10-upstream-stable: N/A "Vulnerability introduced later"
4.19-upstream-stable: N/A "Vulnerability introduced later"
4.9-upstream-stable: N/A "Vulnerability introduced later"
sid: released (5.17.3-1)
5.10-bullseye-security: N/A "Vulnerability introduced later"
4.19-buster-security: N/A "Vulnerability introduced later"
4.9-stretch-security: N/A "Vulnerability introduced later"