| Message ID | 20200512133933.8696-1-pannengyuan@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | i386/kvm: fix a use-after-free when vcpu plug/unplug | expand |
On 5/12/20 3:39 PM, Pan Nengyuan wrote: > 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 <euler.robot@huawei.com> > Signed-off-by: Pan Nengyuan <pannengyuan@huawei.com> > --- > 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; Why set it to NULL? there is no non-NULL check. Anyway if it matters to you, why not do it in qemu_del_vm_change_state_handler()? Otherwise: Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> > + > return 0; > } > >
On 5/12/2020 3:54 PM, Philippe Mathieu-Daudé wrote: > On 5/12/20 3:39 PM, Pan Nengyuan wrote: >> 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 <euler.robot@huawei.com> >> Signed-off-by: Pan Nengyuan <pannengyuan@huawei.com> >> --- >> 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; > > Why set it to NULL? there is no non-NULL check. > > Anyway if it matters to you, why not do it in qemu_del_vm_change_state_handler()? Yes, there is no non-NULL check and it will not be NULL at all. Actually it doesn't matters to me, just habitually set to null after free. I will remove it. Thanks. > > Otherwise: > Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> > >> + >> return 0; >> } >> > > .
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; }
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 <euler.robot@huawei.com> Signed-off-by: Pan Nengyuan <pannengyuan@huawei.com> --- target/i386/cpu.h | 1 + target/i386/kvm.c | 5 ++++- 2 files changed, 5 insertions(+), 1 deletion(-)