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authorWanpeng Li <wanpengli@tencent.com>2021-02-26 15:59:59 +0800
committerPaolo Bonzini <pbonzini@redhat.com>2021-02-26 03:16:50 -0500
commit919f4ebc598701670e80e31573a58f1f2d2bf918 (patch)
tree37723508bc564318907858057ed402ba510f9ac8 /arch/x86
parentffe76c24c5c1851e5ef949d8726d57e78cd0cf34 (diff)
downloadlinux-919f4ebc598701670e80e31573a58f1f2d2bf918.tar.bz2
KVM: x86: hyper-v: Fix Hyper-V context null-ptr-deref
Reported by syzkaller: KASAN: null-ptr-deref in range [0x0000000000000140-0x0000000000000147] CPU: 1 PID: 8370 Comm: syz-executor859 Not tainted 5.11.0-syzkaller #0 RIP: 0010:synic_get arch/x86/kvm/hyperv.c:165 [inline] RIP: 0010:kvm_hv_set_sint_gsi arch/x86/kvm/hyperv.c:475 [inline] RIP: 0010:kvm_hv_irq_routing_update+0x230/0x460 arch/x86/kvm/hyperv.c:498 Call Trace: kvm_set_irq_routing+0x69b/0x940 arch/x86/kvm/../../../virt/kvm/irqchip.c:223 kvm_vm_ioctl+0x12d0/0x2800 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3959 vfs_ioctl fs/ioctl.c:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl fs/ioctl.c:739 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xae Hyper-V context is lazily allocated until Hyper-V specific MSRs are accessed or SynIC is enabled. However, the syzkaller testcase sets irq routing table directly w/o enabling SynIC. This results in null-ptr-deref when accessing SynIC Hyper-V context. This patch fixes it. syzkaller source: https://syzkaller.appspot.com/x/repro.c?x=163342ccd00000 Reported-by: syzbot+6987f3b2dbd9eda95f12@syzkaller.appspotmail.com Fixes: 8f014550dfb1 ("KVM: x86: hyper-v: Make Hyper-V emulation enablement conditional") Signed-off-by: Wanpeng Li <wanpengli@tencent.com> Message-Id: <1614326399-5762-1-git-send-email-wanpengli@tencent.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/kvm/hyperv.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 7d2dae92d638..58fa8c029867 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -159,7 +159,7 @@ static struct kvm_vcpu_hv_synic *synic_get(struct kvm *kvm, u32 vpidx)
struct kvm_vcpu_hv_synic *synic;
vcpu = get_vcpu_by_vpidx(kvm, vpidx);
- if (!vcpu)
+ if (!vcpu || !to_hv_vcpu(vcpu))
return NULL;
synic = to_hv_synic(vcpu);
return (synic->active) ? synic : NULL;