This is a note to let you know that I've just added the patch titled KVM: x86/mmu: fix NULL pointer dereference on guest INVPCID to the 5.10-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: kvm-x86-mmu-fix-null-pointer-dereference-on-guest-invpcid.patch and it can be found in the queue-5.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 9f46c187e2e680ecd9de7983e4d081c3391acc76 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini <pbonzini@xxxxxxxxxx> Date: Fri, 20 May 2022 13:48:11 -0400 Subject: KVM: x86/mmu: fix NULL pointer dereference on guest INVPCID From: Paolo Bonzini <pbonzini@xxxxxxxxxx> commit 9f46c187e2e680ecd9de7983e4d081c3391acc76 upstream. With shadow paging enabled, the INVPCID instruction results in a call to kvm_mmu_invpcid_gva. If INVPCID is executed with CR0.PG=0, the invlpg callback is not set and the result is a NULL pointer dereference. Fix it trivially by checking for mmu->invlpg before every call. There are other possibilities: - check for CR0.PG, because KVM (like all Intel processors after P5) flushes guest TLB on CR0.PG changes so that INVPCID/INVLPG are a nop with paging disabled - check for EFER.LMA, because KVM syncs and flushes when switching MMU contexts outside of 64-bit mode All of these are tricky, go for the simple solution. This is CVE-2022-1789. Reported-by: Yongkang Jia <kangel@xxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx> [fix conflict due to missing b9e5603c2a3accbadfec570ac501a54431a6bdba] Signed-off-by: Vegard Nossum <vegard.nossum@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/x86/kvm/mmu/mmu.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -5178,14 +5178,16 @@ void kvm_mmu_invpcid_gva(struct kvm_vcpu uint i; if (pcid == kvm_get_active_pcid(vcpu)) { - mmu->invlpg(vcpu, gva, mmu->root_hpa); + if (mmu->invlpg) + mmu->invlpg(vcpu, gva, mmu->root_hpa); tlb_flush = true; } for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) { if (VALID_PAGE(mmu->prev_roots[i].hpa) && pcid == kvm_get_pcid(vcpu, mmu->prev_roots[i].pgd)) { - mmu->invlpg(vcpu, gva, mmu->prev_roots[i].hpa); + if (mmu->invlpg) + mmu->invlpg(vcpu, gva, mmu->prev_roots[i].hpa); tlb_flush = true; } } Patches currently in stable-queue which might be from pbonzini@xxxxxxxxxx are queue-5.10/kvm-x86-mmu-fix-null-pointer-dereference-on-guest-invpcid.patch queue-5.10/kvm-x86-properly-handle-apf-vs-disabled-lapic-situation.patch