linux-stable.git/drivers/vhost/vhost.c, branch linux-5.4.y

vhost: fail early when __vhost_add_used() fails

2025-08-28T14:21:27+00:00

[ Upstream commit b4ba1207d45adaafa2982c035898b36af2d3e518 ]

This patch fails vhost_add_used_n() early when __vhost_add_used()
fails to make sure used idx is not updated with stale used ring
information.

Reported-by: Eugenio Pérez 
Signed-off-by: Jason Wang 
Message-Id: <20250714084755.11921-2-jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin 
Tested-by: Lei Yang 
Signed-off-by: Sasha Levin

vhost: Add smp_rmb() in vhost_vq_avail_empty()

2024-05-02T14:18:29+00:00

commit 22e1992cf7b034db5325660e98c41ca5afa5f519 upstream.

A smp_rmb() has been missed in vhost_vq_avail_empty(), spotted by
Will. Otherwise, it's not ensured the available ring entries pushed
by guest can be observed by vhost in time, leading to stale available
ring entries fetched by vhost in vhost_get_vq_desc(), as reported by
Yihuang Yu on NVidia's grace-hopper (ARM64) platform.

  /home/gavin/sandbox/qemu.main/build/qemu-system-aarch64      \
  -accel kvm -machine virt,gic-version=host -cpu host          \
  -smp maxcpus=1,cpus=1,sockets=1,clusters=1,cores=1,threads=1 \
  -m 4096M,slots=16,maxmem=64G                                 \
  -object memory-backend-ram,id=mem0,size=4096M                \
   :                                                           \
  -netdev tap,id=vnet0,vhost=true                              \
  -device virtio-net-pci,bus=pcie.8,netdev=vnet0,mac=52:54:00:f1:26:b0
   :
  guest# netperf -H 10.26.1.81 -l 60 -C -c -t UDP_STREAM
  virtio_net virtio0: output.0:id 100 is not a head!

Add the missed smp_rmb() in vhost_vq_avail_empty(). When tx_can_batch()
returns true, it means there's still pending tx buffers. Since it might
read indices, so it still can bypass the smp_rmb() in vhost_get_vq_desc().
Note that it should be safe until vq->avail_idx is changed by commit
275bf960ac697 ("vhost: better detection of available buffers").

Fixes: 275bf960ac69 ("vhost: better detection of available buffers")
Cc:  # v4.11+
Reported-by: Yihuang Yu 
Suggested-by: Will Deacon 
Signed-off-by: Gavin Shan 
Acked-by: Jason Wang 
Message-Id: <20240328002149.1141302-2-gshan@redhat.com>
Signed-off-by: Michael S. Tsirkin 
Reviewed-by: Stefano Garzarella 
Signed-off-by: Greg Kroah-Hartman

vhost: use kzalloc() instead of kmalloc() followed by memset()

2024-02-23T07:25:08+00:00

commit 4d8df0f5f79f747d75a7d356d9b9ea40a4e4c8a9 upstream.

Use kzalloc() to allocate new zeroed out msg node instead of
memsetting a node allocated with kmalloc().

Signed-off-by: Prathu Baronia 
Message-Id: <20230522085019.42914-1-prathubaronia2011@gmail.com>
Signed-off-by: Michael S. Tsirkin 
Reviewed-by: Stefano Garzarella 
Signed-off-by: Ajay Kaher 
Signed-off-by: Greg Kroah-Hartman

vhost: fix range used in translate_desc()

2023-01-18T10:41:57+00:00

[ Upstream commit 98047313cdb46828093894d0ac8b1183b8b317f9 ]

vhost_iotlb_itree_first() requires `start` and `last` parameters
to search for a mapping that overlaps the range.

In translate_desc() we cyclically call vhost_iotlb_itree_first(),
incrementing `addr` by the amount already translated, so rightly
we move the `start` parameter passed to vhost_iotlb_itree_first(),
but we should hold the `last` parameter constant.

Let's fix it by saving the `last` parameter value before incrementing
`addr` in the loop.

Fixes: a9709d6874d5 ("vhost: convert pre sorted vhost memory array to interval tree")
Acked-by: Jason Wang 
Signed-off-by: Stefano Garzarella 
Message-Id: <20221109102503.18816-3-sgarzare@redhat.com>
Signed-off-by: Michael S. Tsirkin 
Signed-off-by: Sasha Levin

vhost: Fix the calculation in vhost_overflow()

2021-08-26T12:36:16+00:00

[ Upstream commit f7ad318ea0ad58ebe0e595e59aed270bb643b29b ]

This fixes the incorrect calculation for integer overflow
when the last address of iova range is 0xffffffff.

Fixes: ec33d031a14b ("vhost: detect 32 bit integer wrap around")
Reported-by: Jason Wang 
Signed-off-by: Xie Yongji 
Acked-by: Jason Wang 
Link: https://lore.kernel.org/r/20210728130756.97-2-xieyongji@bytedance.com
Signed-off-by: Michael S. Tsirkin 
Signed-off-by: Sasha Levin

vhost: Fix vhost_vq_reset()

2021-04-07T12:47:39+00:00

[ Upstream commit beb691e69f4dec7bfe8b81b509848acfd1f0dbf9 ]

vhost_reset_is_le() is vhost_init_is_le(), and in the case of
cross-endian legacy, vhost_init_is_le() depends on vq->user_be.

vq->user_be is set by vhost_disable_cross_endian().

But in vhost_vq_reset(), we have:

    vhost_reset_is_le(vq);
    vhost_disable_cross_endian(vq);

And so user_be is used before being set.

To fix that, reverse the lines order as there is no other dependency
between them.

Signed-off-by: Laurent Vivier 
Link: https://lore.kernel.org/r/20210312140913.788592-1-lvivier@redhat.com
Signed-off-by: Michael S. Tsirkin 
Signed-off-by: Sasha Levin

vhost: Use vhost_get_used_size() in vhost_vring_set_addr()

2020-10-14T08:32:58+00:00

commit 71878fa46c7e3b40fa7b3f1b6e4ba3f92f1ac359 upstream.

The open-coded computation of the used size doesn't take the event
into account when the VIRTIO_RING_F_EVENT_IDX feature is present.
Fix that by using vhost_get_used_size().

Fixes: 8ea8cf89e19a ("vhost: support event index")
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kurz 
Link: https://lore.kernel.org/r/160171932300.284610.11846106312938909461.stgit@bahia.lan
Signed-off-by: Michael S. Tsirkin 
Signed-off-by: Greg Kroah-Hartman

vhost: Don't call access_ok() when using IOTLB

2020-10-14T08:32:57+00:00

commit 0210a8db2aeca393fb3067e234967877e3146266 upstream.

When the IOTLB device is enabled, the vring addresses we get
from userspace are GIOVAs. It is thus wrong to pass them down
to access_ok() which only takes HVAs.

Access validation is done at prefetch time with IOTLB. Teach
vq_access_ok() about that by moving the (vq->iotlb) check
from vhost_vq_access_ok() to vq_access_ok(). This prevents
vhost_vring_set_addr() to fail when verifying the accesses.
No behavior change for vhost_vq_access_ok().

BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1883084
Fixes: 6b1e6cc7855b ("vhost: new device IOTLB API")
Cc: jasowang@redhat.com
CC: stable@vger.kernel.org # 4.14+
Signed-off-by: Greg Kurz 
Acked-by: Jason Wang 
Link: https://lore.kernel.org/r/160171931213.284610.2052489816407219136.stgit@bahia.lan
Signed-off-by: Michael S. Tsirkin 
Signed-off-by: Greg Kroah-Hartman

Revert "vhost: block speculation of translated descriptors"

2019-09-14T19:21:51+00:00

This reverts commit a89db445fbd7f1f8457b03759aa7343fa530ef6b.

I was hasty to include this patch, and it breaks the build on 32 bit.
Defence in depth is good but let's do it properly.

Cc: stable@vger.kernel.org
Signed-off-by: Michael S. Tsirkin

vhost: make sure log_num < in_num

2019-09-11T19:15:26+00:00

The code assumes log_num < in_num everywhere, and that is true as long as
in_num is incremented by descriptor iov count, and log_num by 1. However
this breaks if there's a zero sized descriptor.

As a result, if a malicious guest creates a vring desc with desc.len = 0,
it may cause the host kernel to crash by overflowing the log array. This
bug can be triggered during the VM migration.

There's no need to log when desc.len = 0, so just don't increment log_num
in this case.

Fixes: 3a4d5c94e959 ("vhost_net: a kernel-level virtio server")
Cc: stable@vger.kernel.org
Reviewed-by: Lidong Chen 
Signed-off-by: ruippan 
Signed-off-by: yongduan 
Acked-by: Michael S. Tsirkin 
Reviewed-by: Tyler Hicks 
Signed-off-by: Michael S. Tsirkin