| Message ID | 20240702020033.139261-2-lulu@redhat.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | virtio-pci: Fix the use of an uninitialized irqfd | expand |
On Tue, Jul 2, 2024 at 10:00 AM Cindy Lu <lulu@redhat.com> wrote: > > The crash was reported in MAC OS and NixOS, here is the link for this bug > https://gitlab.com/qemu-project/qemu/-/issues/2334 > https://gitlab.com/qemu-project/qemu/-/issues/2321 > > The root cause is the function virtio_pci_set_guest_notifiers() was not called > in the virtio_input device. Note that the above two issues seem to be virtio-console instead of virtio-input. And we need to tweak the above a little bit for example what does "in the virtio_input device" mean. For example does it mean irqfd is not used etc. > So the vector_irqfd was not initialized > > So the fix is add the check for vector_irqfd in virtio_pci_get_notifier() Probably "fix is adding". > The function virtio_pci_get_notifier() can also be used while vdev->status > is not VIRTIO_CONFIG_S_DRIVER_OK. In that case, the vector_irqfd could be NULL. > So also add the status check here. Let's explain why this is safe, for example, does it mean the notifiers initialization will be delayed to DRIVER_OK? > > This fix is verified in vyatta,MacOS,NixOS,fedora system. > > The bt tree for this bug is: > Thread 6 "CPU 0/KVM" received signal SIGSEGV, Segmentation fault. > [Switching to Thread 0x7c817be006c0 (LWP 1269146)] > kvm_virtio_pci_vq_vector_use () at ../qemu-9.0.0/hw/virtio/virtio-pci.c:817 > 817 if (irqfd->users == 0) { > (gdb) thread apply all bt > ... > Thread 6 (Thread 0x7c817be006c0 (LWP 1269146) "CPU 0/KVM"): > 0 kvm_virtio_pci_vq_vector_use () at ../qemu-9.0.0/hw/virtio/virtio-pci.c:817 > 1 kvm_virtio_pci_vector_use_one () at ../qemu-9.0.0/hw/virtio/virtio-pci.c:893 > 2 0x00005983657045e2 in memory_region_write_accessor () at ../qemu-9.0.0/system/memory.c:497 > 3 0x0000598365704ba6 in access_with_adjusted_size () at ../qemu-9.0.0/system/memory.c:573 > 4 0x0000598365705059 in memory_region_dispatch_write () at ../qemu-9.0.0/system/memory.c:1528 > 5 0x00005983659b8e1f in flatview_write_continue_step.isra.0 () at ../qemu-9.0.0/system/physmem.c:2713 > 6 0x000059836570ba7d in flatview_write_continue () at ../qemu-9.0.0/system/physmem.c:2743 > 7 flatview_write () at ../qemu-9.0.0/system/physmem.c:2774 > 8 0x000059836570bb76 in address_space_write () at ../qemu-9.0.0/system/physmem.c:2894 > 9 0x0000598365763afe in address_space_rw () at ../qemu-9.0.0/system/physmem.c:2904 > 10 kvm_cpu_exec () at ../qemu-9.0.0/accel/kvm/kvm-all.c:2917 > 11 0x000059836576656e in kvm_vcpu_thread_fn () at ../qemu-9.0.0/accel/kvm/kvm-accel-ops.c:50 > 12 0x0000598365926ca8 in qemu_thread_start () at ../qemu-9.0.0/util/qemu-thread-posix.c:541 > 13 0x00007c8185bcd1cf in ??? () at /usr/lib/libc.so.6 > 14 0x00007c8185c4e504 in clone () at /usr/lib/libc.so.6 > > Fixes: 2ce6cff94d ("virtio-pci: fix use of a released vector") > Cc: qemu-stable@nongnu.org > Signed-off-by: Cindy Lu <lulu@redhat.com> > --- > hw/virtio/virtio-pci.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c > index b1d02f4b3d..6b62165ef6 100644 > --- a/hw/virtio/virtio-pci.c > +++ b/hw/virtio/virtio-pci.c > @@ -860,6 +860,9 @@ static int virtio_pci_get_notifier(VirtIOPCIProxy *proxy, int queue_no, > VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus); > VirtQueue *vq; > > + if (!proxy->vector_irqfd && vdev->status & VIRTIO_CONFIG_S_DRIVER_OK) > + return -1; > + > if (queue_no == VIRTIO_CONFIG_IRQ_IDX) { > *n = virtio_config_get_guest_notifier(vdev); > *vector = vdev->config_vector; > -- > 2.45.0 Thanks
diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c index b1d02f4b3d..6b62165ef6 100644 --- a/hw/virtio/virtio-pci.c +++ b/hw/virtio/virtio-pci.c @@ -860,6 +860,9 @@ static int virtio_pci_get_notifier(VirtIOPCIProxy *proxy, int queue_no, VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus); VirtQueue *vq; + if (!proxy->vector_irqfd && vdev->status & VIRTIO_CONFIG_S_DRIVER_OK) + return -1; + if (queue_no == VIRTIO_CONFIG_IRQ_IDX) { *n = virtio_config_get_guest_notifier(vdev); *vector = vdev->config_vector;
The crash was reported in MAC OS and NixOS, here is the link for this bug https://gitlab.com/qemu-project/qemu/-/issues/2334 https://gitlab.com/qemu-project/qemu/-/issues/2321 The root cause is the function virtio_pci_set_guest_notifiers() was not called in the virtio_input device.So the vector_irqfd was not initialized So the fix is add the check for vector_irqfd in virtio_pci_get_notifier() The function virtio_pci_get_notifier() can also be used while vdev->status is not VIRTIO_CONFIG_S_DRIVER_OK. In that case, the vector_irqfd could be NULL. So also add the status check here. This fix is verified in vyatta,MacOS,NixOS,fedora system. The bt tree for this bug is: Thread 6 "CPU 0/KVM" received signal SIGSEGV, Segmentation fault. [Switching to Thread 0x7c817be006c0 (LWP 1269146)] kvm_virtio_pci_vq_vector_use () at ../qemu-9.0.0/hw/virtio/virtio-pci.c:817 817 if (irqfd->users == 0) { (gdb) thread apply all bt ... Thread 6 (Thread 0x7c817be006c0 (LWP 1269146) "CPU 0/KVM"): 0 kvm_virtio_pci_vq_vector_use () at ../qemu-9.0.0/hw/virtio/virtio-pci.c:817 1 kvm_virtio_pci_vector_use_one () at ../qemu-9.0.0/hw/virtio/virtio-pci.c:893 2 0x00005983657045e2 in memory_region_write_accessor () at ../qemu-9.0.0/system/memory.c:497 3 0x0000598365704ba6 in access_with_adjusted_size () at ../qemu-9.0.0/system/memory.c:573 4 0x0000598365705059 in memory_region_dispatch_write () at ../qemu-9.0.0/system/memory.c:1528 5 0x00005983659b8e1f in flatview_write_continue_step.isra.0 () at ../qemu-9.0.0/system/physmem.c:2713 6 0x000059836570ba7d in flatview_write_continue () at ../qemu-9.0.0/system/physmem.c:2743 7 flatview_write () at ../qemu-9.0.0/system/physmem.c:2774 8 0x000059836570bb76 in address_space_write () at ../qemu-9.0.0/system/physmem.c:2894 9 0x0000598365763afe in address_space_rw () at ../qemu-9.0.0/system/physmem.c:2904 10 kvm_cpu_exec () at ../qemu-9.0.0/accel/kvm/kvm-all.c:2917 11 0x000059836576656e in kvm_vcpu_thread_fn () at ../qemu-9.0.0/accel/kvm/kvm-accel-ops.c:50 12 0x0000598365926ca8 in qemu_thread_start () at ../qemu-9.0.0/util/qemu-thread-posix.c:541 13 0x00007c8185bcd1cf in ??? () at /usr/lib/libc.so.6 14 0x00007c8185c4e504 in clone () at /usr/lib/libc.so.6 Fixes: 2ce6cff94d ("virtio-pci: fix use of a released vector") Cc: qemu-stable@nongnu.org Signed-off-by: Cindy Lu <lulu@redhat.com> --- hw/virtio/virtio-pci.c | 3 +++ 1 file changed, 3 insertions(+)