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| author | Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> | 2020-10-04 01:27:07 +0200 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2020-10-21 23:48:49 +0200 |
| commit | f6426ab9c957e97418ac5b0466538792767b1738 (patch) | |
| tree | cd6c126744db5edca31d1b8596404daa66bc14ae /arch/x86 | |
| parent | KVM: nSVM: implement on demand allocation of the nested state (diff) | |
| download | linux-f6426ab9c957e97418ac5b0466538792767b1738.tar.xz linux-f6426ab9c957e97418ac5b0466538792767b1738.zip | |
KVM: SVM: Initialize prev_ga_tag before use
The function amd_ir_set_vcpu_affinity makes use of the parameter struct
amd_iommu_pi_data.prev_ga_tag to determine if it should delete struct
amd_iommu_pi_data from a list when not running in AVIC mode.
However, prev_ga_tag is initialized only when AVIC is enabled. The non-zero
uninitialized value can cause unintended code path, which ends up making
use of the struct vcpu_svm.ir_list and ir_list_lock without being
initialized (since they are intended only for the AVIC case).
This triggers NULL pointer dereference bug in the function vm_ir_list_del
with the following call trace:
svm_update_pi_irte+0x3c2/0x550 [kvm_amd]
? proc_create_single_data+0x41/0x50
kvm_arch_irq_bypass_add_producer+0x40/0x60 [kvm]
__connect+0x5f/0xb0 [irqbypass]
irq_bypass_register_producer+0xf8/0x120 [irqbypass]
vfio_msi_set_vector_signal+0x1de/0x2d0 [vfio_pci]
vfio_msi_set_block+0x77/0xe0 [vfio_pci]
vfio_pci_set_msi_trigger+0x25c/0x2f0 [vfio_pci]
vfio_pci_set_irqs_ioctl+0x88/0xb0 [vfio_pci]
vfio_pci_ioctl+0x2ea/0xed0 [vfio_pci]
? alloc_file_pseudo+0xa5/0x100
vfio_device_fops_unl_ioctl+0x26/0x30 [vfio]
? vfio_device_fops_unl_ioctl+0x26/0x30 [vfio]
__x64_sys_ioctl+0x96/0xd0
do_syscall_64+0x37/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Therefore, initialize prev_ga_tag to zero before use. This should be safe
because ga_tag value 0 is invalid (see function avic_vm_init).
Fixes: dfa20099e26e ("KVM: SVM: Refactor AVIC vcpu initialization into avic_init_vcpu()")
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Message-Id: <20201003232707.4662-1-suravee.suthikulpanit@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/kvm/svm/avic.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c index f73f84d56452..8c550999ace0 100644 --- a/arch/x86/kvm/svm/avic.c +++ b/arch/x86/kvm/svm/avic.c @@ -866,6 +866,7 @@ int svm_update_pi_irte(struct kvm *kvm, unsigned int host_irq, * - Tell IOMMU to use legacy mode for this interrupt. * - Retrieve ga_tag of prior interrupt remapping data. */ + pi.prev_ga_tag = 0; pi.is_guest_mode = false; ret = irq_set_vcpu_affinity(host_irq, &pi); |