From 16b7f98db096e8e8829bc0b89aa7afbf6afd50f0 Mon Sep 17 00:00:00 2001 From: Chen Qun Date: Thu, 10 Feb 2022 11:16:26 +0800 Subject: [PATCH] virtio: bugfix: add rcu_read_lock when vring_avail_idx is called viring_avail_idx should be called within rcu_read_lock(), or may get NULL caches in vring_get_region_caches() and trigger assert(). Signed-off-by: Jinhua Cao --- ...d-rcu_read_lock-when-vring_avail_idx.patch | 38 +++++++++++++++++++ 1 file changed, 38 insertions(+) create mode 100644 virtio-bugfix-add-rcu_read_lock-when-vring_avail_idx.patch diff --git a/virtio-bugfix-add-rcu_read_lock-when-vring_avail_idx.patch b/virtio-bugfix-add-rcu_read_lock-when-vring_avail_idx.patch new file mode 100644 index 0000000..39551a7 --- /dev/null +++ b/virtio-bugfix-add-rcu_read_lock-when-vring_avail_idx.patch @@ -0,0 +1,38 @@ +From 41aa66e37d04246d48b5417c57967425ecc466a0 Mon Sep 17 00:00:00 2001 +From: Jinhua Cao +Date: Thu, 10 Feb 2022 11:16:26 +0800 +Subject: [PATCH] virtio: bugfix: add rcu_read_lock when vring_avail_idx is + called + +viring_avail_idx should be called within rcu_read_lock(), +or may get NULL caches in vring_get_region_caches() and +trigger assert(). + +Signed-off-by: Jinhua Cao +--- + hw/virtio/virtio.c | 2 ++ + 1 file changed, 2 insertions(+) + +diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c +index 007f4c9e26..0af9684881 100644 +--- a/hw/virtio/virtio.c ++++ b/hw/virtio/virtio.c +@@ -2864,6 +2864,7 @@ static void check_vring_avail_num(VirtIODevice *vdev, int index) + { + uint16_t nheads; + ++ rcu_read_lock(); + /* Check it isn't doing strange things with descriptor numbers. */ + nheads = vring_avail_idx(&vdev->vq[index]) - vdev->vq[index].last_avail_idx; + if (nheads > vdev->vq[index].vring.num) { +@@ -2874,6 +2875,7 @@ static void check_vring_avail_num(VirtIODevice *vdev, int index) + vring_avail_idx(&vdev->vq[index]), + vdev->vq[index].last_avail_idx, nheads); + } ++ rcu_read_unlock(); + } + + int virtio_save(VirtIODevice *vdev, QEMUFile *f) +-- +2.27.0 +