From f55e32a7892964908252bb5fe3719bb22c2de2dd Mon Sep 17 00:00:00 2001 From: "Dr. David Alan Gilbert" Date: Tue, 26 Nov 2019 13:27:55 +0100 Subject: [PATCH] vhost: fix vhost_log size overflow during migration RH-Author: Dr. David Alan Gilbert Message-id: <20191126132755.42248-2-dgilbert@redhat.com> Patchwork-id: 92686 O-Subject: [RHEL-7.8 qemu-kvm-rhev PATCH 1/1] vhost: fix vhost_log size overflow during migration Bugzilla: 1775251 RH-Acked-by: Laszlo Ersek RH-Acked-by: Peter Xu RH-Acked-by: Juan Quintela From: Li Hangjing When a guest which doesn't support multiqueue is migrated with a multi queues vhost-user-blk deivce, a crash will occur like: 0 qemu_memfd_alloc (name=, size=562949953421312, seals=, fd=0x7f87171fe8b4, errp=0x7f87171fe8a8) at util/memfd.c:153 1 0x00007f883559d7cf in vhost_log_alloc (size=70368744177664, share=true) at hw/virtio/vhost.c:186 2 0x00007f88355a0758 in vhost_log_get (listener=0x7f8838bd7940, enable=1) at qemu-2-12/hw/virtio/vhost.c:211 3 vhost_dev_log_resize (listener=0x7f8838bd7940, enable=1) at hw/virtio/vhost.c:263 4 vhost_migration_log (listener=0x7f8838bd7940, enable=1) at hw/virtio/vhost.c:787 5 0x00007f88355463d6 in memory_global_dirty_log_start () at memory.c:2503 6 0x00007f8835550577 in ram_init_bitmaps (f=0x7f88384ce600, opaque=0x7f8836024098) at migration/ram.c:2173 7 ram_init_all (f=0x7f88384ce600, opaque=0x7f8836024098) at migration/ram.c:2192 8 ram_save_setup (f=0x7f88384ce600, opaque=0x7f8836024098) at migration/ram.c:2219 9 0x00007f88357a419d in qemu_savevm_state_setup (f=0x7f88384ce600) at migration/savevm.c:1002 10 0x00007f883579fc3e in migration_thread (opaque=0x7f8837530400) at migration/migration.c:2382 11 0x00007f8832447893 in start_thread () from /lib64/libpthread.so.0 12 0x00007f8832178bfd in clone () from /lib64/libc.so.6 This is because vhost_get_log_size() returns a overflowed vhost-log size. In this function, it uses the uninitialized variable vqs->used_phys and vqs->used_size to get the vhost-log size. Signed-off-by: Li Hangjing Reviewed-by: Xie Yongji Reviewed-by: Chai Wen Message-Id: <20190603061524.24076-1-lihangjing@baidu.com> Cc: qemu-stable@nongnu.org Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin (cherry picked from commit 240e647a14df9677b3a501f7b8b870e40aac3fd5) Signed-off-by: Miroslav Rezanina --- hw/virtio/vhost.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c index 1ae68ff..7bdc9c4 100644 --- a/hw/virtio/vhost.c +++ b/hw/virtio/vhost.c @@ -131,6 +131,11 @@ static int vhost_sync_dirty_bitmap(struct vhost_dev *dev, } for (i = 0; i < dev->nvqs; ++i) { struct vhost_virtqueue *vq = dev->vqs + i; + + if (!vq->used_phys && !vq->used_size) { + continue; + } + vhost_dev_sync_region(dev, section, start_addr, end_addr, vq->used_phys, range_get_last(vq->used_phys, vq->used_size)); } @@ -168,6 +173,11 @@ static uint64_t vhost_get_log_size(struct vhost_dev *dev) } for (i = 0; i < dev->nvqs; ++i) { struct vhost_virtqueue *vq = dev->vqs + i; + + if (!vq->used_phys && !vq->used_size) { + continue; + } + uint64_t last = vq->used_phys + vq->used_size - 1; log_size = MAX(log_size, last / VHOST_LOG_CHUNK + 1); } -- 1.8.3.1