This is a note to let you know that I've just added the patch titled
KVM: arm64: Check for kvm_vma_mte_allowed in the critical section
to the 6.2-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-arm64-check-for-kvm_vma_mte_allowed-in-the-critical-section.patch
and it can be found in the queue-6.2 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 8c2e8ac8ad4be68409e806ce1cc78fc7a04539f3 Mon Sep 17 00:00:00 2001
From: Marc Zyngier <maz@xxxxxxxxxx>
Date: Thu, 16 Mar 2023 17:45:46 +0000
Subject: KVM: arm64: Check for kvm_vma_mte_allowed in the critical section
From: Marc Zyngier <maz@xxxxxxxxxx>
commit 8c2e8ac8ad4be68409e806ce1cc78fc7a04539f3 upstream.
On page fault, we find about the VMA that backs the page fault
early on, and quickly release the mmap_read_lock. However, using
the VMA pointer after the critical section is pretty dangerous,
as a teardown may happen in the meantime and the VMA be long gone.
Move the sampling of the MTE permission early, and NULL-ify the
VMA pointer after that, just to be on the safe side.
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/20230316174546.3777507-3-maz@xxxxxxxxxx
Signed-off-by: Oliver Upton <oliver.upton@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm64/kvm/mmu.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -1218,7 +1218,7 @@ static int user_mem_abort(struct kvm_vcp
{
int ret = 0;
bool write_fault, writable, force_pte = false;
- bool exec_fault;
+ bool exec_fault, mte_allowed;
bool device = false;
unsigned long mmu_seq;
struct kvm *kvm = vcpu->kvm;
@@ -1309,6 +1309,10 @@ static int user_mem_abort(struct kvm_vcp
fault_ipa &= ~(vma_pagesize - 1);
gfn = fault_ipa >> PAGE_SHIFT;
+ mte_allowed = kvm_vma_mte_allowed(vma);
+
+ /* Don't use the VMA after the unlock -- it may have vanished */
+ vma = NULL;
/*
* Read mmu_invalidate_seq so that KVM can detect if the results of
@@ -1379,7 +1383,7 @@ static int user_mem_abort(struct kvm_vcp
if (fault_status != ESR_ELx_FSC_PERM && !device && kvm_has_mte(kvm)) {
/* Check the VMM hasn't introduced a new disallowed VMA */
- if (kvm_vma_mte_allowed(vma)) {
+ if (mte_allowed) {
sanitise_mte_tags(kvm, pfn, vma_pagesize);
} else {
ret = -EFAULT;
Patches currently in stable-queue which might be from maz@xxxxxxxxxx are
queue-6.2/kvm-arm64-pmu-fix-get_one_reg-for-vpmc-regs-to-return-the-current-value.patch
queue-6.2/kvm-arm64-disable-interrupts-while-walking-userspace-pts.patch
queue-6.2/kvm-arm64-pmu-don-t-save-pmcr_el0.-c-p-for-the-vcpu.patch
queue-6.2/kvm-arm64-retry-fault-if-vma_lookup-results-become-invalid.patch
queue-6.2/kvm-arm64-check-for-kvm_vma_mte_allowed-in-the-critical-section.patch
