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[PATCH] i386/kvm: fix a use-after-free when vcpu plug/unplug
From: |
Pan Nengyuan |
Subject: |
[PATCH] i386/kvm: fix a use-after-free when vcpu plug/unplug |
Date: |
Tue, 12 May 2020 09:39:33 -0400 |
When we hotplug vcpus, cpu_update_state is added to vm_change_state_head
in kvm_arch_init_vcpu(). But it forgot to delete in kvm_arch_destroy_vcpu()
after
unplug. Then it will cause a use-after-free access. This patch delete it in
kvm_arch_destroy_vcpu() to fix that.
Reproducer:
virsh setvcpus vm1 4 --live
virsh setvcpus vm1 2 --live
virsh suspend vm1
virsh resume vm1
The UAF stack:
==qemu-system-x86_64==28233==ERROR: AddressSanitizer: heap-use-after-free on
address 0x62e00002e798 at pc 0x5573c6917d9e bp 0x7fff07139e50 sp 0x7fff07139e40
WRITE of size 1 at 0x62e00002e798 thread T0
#0 0x5573c6917d9d in cpu_update_state /mnt/sdb/qemu/target/i386/kvm.c:742
#1 0x5573c699121a in vm_state_notify /mnt/sdb/qemu/vl.c:1290
#2 0x5573c636287e in vm_prepare_start /mnt/sdb/qemu/cpus.c:2144
#3 0x5573c6362927 in vm_start /mnt/sdb/qemu/cpus.c:2150
#4 0x5573c71e8304 in qmp_cont /mnt/sdb/qemu/monitor/qmp-cmds.c:173
#5 0x5573c727cb1e in qmp_marshal_cont qapi/qapi-commands-misc.c:835
#6 0x5573c7694c7a in do_qmp_dispatch /mnt/sdb/qemu/qapi/qmp-dispatch.c:132
#7 0x5573c7694c7a in qmp_dispatch /mnt/sdb/qemu/qapi/qmp-dispatch.c:175
#8 0x5573c71d9110 in monitor_qmp_dispatch /mnt/sdb/qemu/monitor/qmp.c:145
#9 0x5573c71dad4f in monitor_qmp_bh_dispatcher
/mnt/sdb/qemu/monitor/qmp.c:234
Reported-by: Euler Robot <address@hidden>
Signed-off-by: Pan Nengyuan <address@hidden>
---
target/i386/cpu.h | 1 +
target/i386/kvm.c | 5 ++++-
2 files changed, 5 insertions(+), 1 deletion(-)
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index e818fc712a..afbd11b7a3 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -1631,6 +1631,7 @@ struct X86CPU {
CPUNegativeOffsetState neg;
CPUX86State env;
+ VMChangeStateEntry *vmsentry;
uint64_t ucode_rev;
diff --git a/target/i386/kvm.c b/target/i386/kvm.c
index 4901c6dd74..ff2848357e 100644
--- a/target/i386/kvm.c
+++ b/target/i386/kvm.c
@@ -1770,7 +1770,7 @@ int kvm_arch_init_vcpu(CPUState *cs)
}
}
- qemu_add_vm_change_state_handler(cpu_update_state, env);
+ cpu->vmsentry = qemu_add_vm_change_state_handler(cpu_update_state, env);
c = cpuid_find_entry(&cpuid_data.cpuid, 1, 0);
if (c) {
@@ -1883,6 +1883,9 @@ int kvm_arch_destroy_vcpu(CPUState *cs)
env->nested_state = NULL;
}
+ qemu_del_vm_change_state_handler(cpu->vmsentry);
+ cpu->vmsentry = NULL;
+
return 0;
}
--
2.18.2
- [PATCH] i386/kvm: fix a use-after-free when vcpu plug/unplug,
Pan Nengyuan <=