From c3fd706165e9875a10606453ee2785dd51e987a5 Mon Sep 17 00:00:00 2001 From: Yuri Benditovich Date: Mon, 15 Mar 2021 13:59:36 +0200 Subject: [PATCH] virtio-pci: add check for vdev in virtio_pci_isr_read https://bugzilla.redhat.com/show_bug.cgi?id=1743098 This commit completes the solution of segfault in hot unplug flow (by commit ccec7e9603f446fe75c6c563ba335c00cfda6a06). Added missing check for vdev in virtio_pci_isr_read. Typical stack of crash: virtio_pci_isr_read ../hw/virtio/virtio-pci.c:1365 with proxy-vdev = 0 memory_region_read_accessor at ../softmmu/memory.c:442 access_with_adjusted_size at ../softmmu/memory.c:552 memory_region_dispatch_read1 at ../softmmu/memory.c:1420 memory_region_dispatch_read at ../softmmu/memory.c:1449 flatview_read_continue at ../softmmu/physmem.c:2822 flatview_read at ../softmmu/physmem.c:2862 address_space_read_full at ../softmmu/physmem.c:2875 Signed-off-by: Yuri Benditovich Message-Id: <20210315115937.14286-2-yuri.benditovich@daynix.com> Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- hw/virtio/virtio-pci.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c index 883045a223..4a3dcee771 100644 --- a/hw/virtio/virtio-pci.c +++ b/hw/virtio/virtio-pci.c @@ -1364,9 +1364,14 @@ static uint64_t virtio_pci_isr_read(void *opaque, hwaddr addr, { VirtIOPCIProxy *proxy = opaque; VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus); - uint64_t val = qatomic_xchg(&vdev->isr, 0); - pci_irq_deassert(&proxy->pci_dev); + uint64_t val; + if (vdev == NULL) { + return 0; + } + + val = qatomic_xchg(&vdev->isr, 0); + pci_irq_deassert(&proxy->pci_dev); return val; }