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authorPaolo Bonzini <pbonzini@redhat.com>2022-04-06 20:13:42 +0300
committerPaolo Bonzini <pbonzini@redhat.com>2022-04-06 20:26:30 +0300
commit5593473a1e6c743764b08e3b6071cb43b5cfa6c4 (patch)
tree344aca3aecf659cba08717558f1ada346fcfd371 /virt/kvm
parentc1be1ef1b4a7589878d63673b7b322856989064e (diff)
downloadlinux-5593473a1e6c743764b08e3b6071cb43b5cfa6c4.tar.xz
KVM: avoid NULL pointer dereference in kvm_dirty_ring_push
kvm_vcpu_release() will call kvm_dirty_ring_free(), freeing ring->dirty_gfns and setting it to NULL. Afterwards, it calls kvm_arch_vcpu_destroy(). However, if closing the file descriptor races with KVM_RUN in such away that vcpu->arch.st.preempted == 0, the following call stack leads to a NULL pointer dereference in kvm_dirty_run_push(): mark_page_dirty_in_slot+0x192/0x270 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3171 kvm_steal_time_set_preempted arch/x86/kvm/x86.c:4600 [inline] kvm_arch_vcpu_put+0x34e/0x5b0 arch/x86/kvm/x86.c:4618 vcpu_put+0x1b/0x70 arch/x86/kvm/../../../virt/kvm/kvm_main.c:211 vmx_free_vcpu+0xcb/0x130 arch/x86/kvm/vmx/vmx.c:6985 kvm_arch_vcpu_destroy+0x76/0x290 arch/x86/kvm/x86.c:11219 kvm_vcpu_destroy arch/x86/kvm/../../../virt/kvm/kvm_main.c:441 [inline] The fix is to release the dirty page ring after kvm_arch_vcpu_destroy has run. Reported-by: Qiuhao Li <qiuhao@sysec.org> Reported-by: Gaoning Pan <pgn@zju.edu.cn> Reported-by: Yongkang Jia <kangel@zju.edu.cn> Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'virt/kvm')
-rw-r--r--virt/kvm/kvm_main.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 70e05af5ebea..b22f380e3347 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -434,8 +434,8 @@ static void kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id)
static void kvm_vcpu_destroy(struct kvm_vcpu *vcpu)
{
- kvm_dirty_ring_free(&vcpu->dirty_ring);
kvm_arch_vcpu_destroy(vcpu);
+ kvm_dirty_ring_free(&vcpu->dirty_ring);
/*
* No need for rcu_read_lock as VCPU_RUN is the only place that changes