The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y git checkout FETCH_HEAD git cherry-pick -x 6ddb4f372fc63210034b903d96ebbeb3c7195adb # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024051331-relieving-showcase-24cd@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^..

Possible dependencies:

6ddb4f372fc6 ("KVM: arm64: vgic-v2: Check for non-NULL vCPU in vgic_v2_parse_attr()") 4e7728c81a54 ("KVM: arm64: vgic-v2: Use cpuid from userspace as vcpu_id")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 6ddb4f372fc63210034b903d96ebbeb3c7195adb Mon Sep 17 00:00:00 2001 From: Oliver Upton oliver.upton@linux.dev Date: Wed, 24 Apr 2024 17:39:58 +0000 Subject: [PATCH] KVM: arm64: vgic-v2: Check for non-NULL vCPU in vgic_v2_parse_attr()

vgic_v2_parse_attr() is responsible for finding the vCPU that matches the user-provided CPUID, which (of course) may not be valid. If the ID is invalid, kvm_get_vcpu_by_id() returns NULL, which isn't handled gracefully.

Similar to the GICv3 uaccess flow, check that kvm_get_vcpu_by_id() actually returns something and fail the ioctl if not.

Cc: stable@vger.kernel.org Fixes: 7d450e282171 ("KVM: arm/arm64: vgic-new: Add userland access to VGIC dist registers") Reported-by: Alexander Potapenko glider@google.com Tested-by: Alexander Potapenko glider@google.com Reviewed-by: Alexander Potapenko glider@google.com Reviewed-by: Marc Zyngier maz@kernel.org Link: https://lore.kernel.org/r/20240424173959.3776798-2-oliver.upton@linux.dev Signed-off-by: Oliver Upton oliver.upton@linux.dev

diff --git a/arch/arm64/kvm/vgic/vgic-kvm-device.c b/arch/arm64/kvm/vgic/vgic-kvm-device.c index f48b8dab8b3d..1d26bb5b02f4 100644 --- a/arch/arm64/kvm/vgic/vgic-kvm-device.c +++ b/arch/arm64/kvm/vgic/vgic-kvm-device.c @@ -338,12 +338,12 @@ int kvm_register_vgic_device(unsigned long type) int vgic_v2_parse_attr(struct kvm_device *dev, struct kvm_device_attr *attr, struct vgic_reg_attr *reg_attr) { - int cpuid; + int cpuid = FIELD_GET(KVM_DEV_ARM_VGIC_CPUID_MASK, attr->attr);

- cpuid = FIELD_GET(KVM_DEV_ARM_VGIC_CPUID_MASK, attr->attr); - - reg_attr->vcpu = kvm_get_vcpu_by_id(dev->kvm, cpuid); reg_attr->addr = attr->attr & KVM_DEV_ARM_VGIC_OFFSET_MASK; + reg_attr->vcpu = kvm_get_vcpu_by_id(dev->kvm, cpuid); + if (!reg_attr->vcpu) + return -EINVAL;

return 0; }