kernel/linux.git/drivers/vhost/vsock.c, branch v5.10.257

vhost/vsock: improve RCU read sections around vhost_vsock_get()

2026-01-19T12:11:47+00:00

[ Upstream commit d8ee3cfdc89b75dc059dc21c27bef2c1440f67eb ] vhost_vsock_get() uses hash_for_each_possible_rcu() to find the `vhost_vsock` associated with the `guest_cid`. hash_for_each_possible_rcu() should only be called within an RCU read section, as mentioned in the following comment in include/linux/rculist.h: /** * hlist_for_each_entry_rcu - iterate over rcu list of given type * @pos: the type * to use as a loop cursor. * @head: the head for your list. * @member: the name of the hlist_node within the struct. * @cond: optional lockdep expression if called from non-RCU protection. * * This list-traversal primitive may safely run concurrently with * the _rcu list-mutation primitives such as hlist_add_head_rcu() * as long as the traversal is guarded by rcu_read_lock(). */ Currently, all calls to vhost_vsock_get() are between rcu_read_lock() and rcu_read_unlock() except for calls in vhost_vsock_set_cid() and vhost_vsock_reset_orphans(). In both cases, the current code is safe, but we can make improvements to make it more robust. About vhost_vsock_set_cid(), when building the kernel with CONFIG_PROVE_RCU_LIST enabled, we get the following RCU warning when the user space issues `ioctl(dev, VHOST_VSOCK_SET_GUEST_CID, ...)` : WARNING: suspicious RCU usage 6.18.0-rc7 #62 Not tainted ----------------------------- drivers/vhost/vsock.c:74 RCU-list traversed in non-reader section!! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 1 lock held by rpc-libvirtd/3443: #0: ffffffffc05032a8 (vhost_vsock_mutex){+.+.}-{4:4}, at: vhost_vsock_dev_ioctl+0x2ff/0x530 [vhost_vsock] stack backtrace: CPU: 2 UID: 0 PID: 3443 Comm: rpc-libvirtd Not tainted 6.18.0-rc7 #62 PREEMPT(none) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-7.fc42 06/10/2025 Call Trace: dump_stack_lvl+0x75/0xb0 dump_stack+0x14/0x1a lockdep_rcu_suspicious.cold+0x4e/0x97 vhost_vsock_get+0x8f/0xa0 [vhost_vsock] vhost_vsock_dev_ioctl+0x307/0x530 [vhost_vsock] __x64_sys_ioctl+0x4f2/0xa00 x64_sys_call+0xed0/0x1da0 do_syscall_64+0x73/0xfa0 entry_SYSCALL_64_after_hwframe+0x76/0x7e ... This is not a real problem, because the vhost_vsock_get() caller, i.e. vhost_vsock_set_cid(), holds the `vhost_vsock_mutex` used by the hash table writers. Anyway, to prevent that warning, add lockdep_is_held() condition to hash_for_each_possible_rcu() to verify that either the caller is in an RCU read section or `vhost_vsock_mutex` is held when CONFIG_PROVE_RCU_LIST is enabled; and also clarify the comment for vhost_vsock_get() to better describe the locking requirements and the scope of the returned pointer validity. About vhost_vsock_reset_orphans(), currently this function is only called via vsock_for_each_connected_socket(), which holds the `vsock_table_lock` spinlock (which is also an RCU read-side critical section). However, add an explicit RCU read lock there to make the code more robust and explicit about the RCU requirements, and to prevent issues if the calling context changes in the future or if vhost_vsock_reset_orphans() is called from other contexts. Fixes: 834e772c8db0 ("vhost/vsock: fix use-after-free in network stack callers") Cc: stefanha@redhat.com Signed-off-by: Stefano Garzarella Reviewed-by: Stefan Hajnoczi Message-Id: <20251126133826.142496-1-sgarzare@redhat.com> Message-ID: <20251126210313.GA499503@fedora> Acked-by: Jason Wang Signed-off-by: Michael S. Tsirkin Signed-off-by: Sasha Levin

vhost/vsock: Fix error handling in vhost_vsock_init()

2023-01-14T09:16:46+00:00

[ Upstream commit 7a4efe182ca61fb3e5307e69b261c57cbf434cd4 ] A problem about modprobe vhost_vsock failed is triggered with the following log given: modprobe: ERROR: could not insert 'vhost_vsock': Device or resource busy The reason is that vhost_vsock_init() returns misc_register() directly without checking its return value, if misc_register() failed, it returns without calling vsock_core_unregister() on vhost_transport, resulting the vhost_vsock can never be installed later. A simple call graph is shown as below: vhost_vsock_init() vsock_core_register() # register vhost_transport misc_register() device_create_with_groups() device_create_groups_vargs() dev = kzalloc(...) # OOM happened # return without unregister vhost_transport Fix by calling vsock_core_unregister() when misc_register() returns error. Fixes: 433fc58e6bf2 ("VSOCK: Introduce vhost_vsock.ko") Signed-off-by: Yuan Can Message-Id: <20221108101705.45981-1-yuancan@huawei.com> Signed-off-by: Michael S. Tsirkin Reviewed-by: Stefano Garzarella Acked-by: Jason Wang Signed-off-by: Sasha Levin

vhost/vsock: Use kvmalloc/kvfree for larger packets.

2022-10-26T11:25:22+00:00

[ Upstream commit 0e3f72931fc47bb81686020cc643cde5d9cd0bb8 ] When copying a large file over sftp over vsock, data size is usually 32kB, and kmalloc seems to fail to try to allocate 32 32kB regions. vhost-5837: page allocation failure: order:4, mode:0x24040c0 Call Trace: [] dump_stack+0x97/0xdb [] warn_alloc_failed+0x10f/0x138 [] ? __alloc_pages_direct_compact+0x38/0xc8 [] __alloc_pages_nodemask+0x84c/0x90d [] alloc_kmem_pages+0x17/0x19 [] kmalloc_order_trace+0x2b/0xdb [] __kmalloc+0x177/0x1f7 [] ? copy_from_iter+0x8d/0x31d [] vhost_vsock_handle_tx_kick+0x1fa/0x301 [vhost_vsock] [] vhost_worker+0xf7/0x157 [vhost] [] kthread+0xfd/0x105 [] ? vhost_dev_set_owner+0x22e/0x22e [vhost] [] ? flush_kthread_worker+0xf3/0xf3 [] ret_from_fork+0x4e/0x80 [] ? flush_kthread_worker+0xf3/0xf3 Work around by doing kvmalloc instead. Fixes: 433fc58e6bf2 ("VSOCK: Introduce vhost_vsock.ko") Signed-off-by: Junichi Uekawa Reviewed-by: Stefano Garzarella Acked-by: Michael S. Tsirkin Link: https://lore.kernel.org/r/20220928064538.667678-1-uekawa@chromium.org Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

vsock: each transport cycles only on its own sockets

2022-03-23T08:13:27+00:00

[ Upstream commit 8e6ed963763fe21429eabfc76c69ce2b0163a3dd ] When iterating over sockets using vsock_for_each_connected_socket, make sure that a transport filters out sockets that don't belong to the transport. There actually was an issue caused by this; in a nested VM configuration, destroying the nested VM (which often involves the closing of /dev/vhost-vsock if there was h2g connections to the nested VM) kills not only the h2g connections, but also all existing g2h connections to the (outmost) host which are totally unrelated. Tested: Executed the following steps on Cuttlefish (Android running on a VM) [1]: (1) Enter into an `adb shell` session - to have a g2h connection inside the VM, (2) open and then close /dev/vhost-vsock by `exec 3< /dev/vhost-vsock && exec 3<&-`, (3) observe that the adb session is not reset. [1] https://android.googlesource.com/device/google/cuttlefish/ Fixes: c0cfa2d8a788 ("vsock: add multi-transports support") Reviewed-by: Stefano Garzarella Acked-by: Michael S. Tsirkin Signed-off-by: Jiyong Park Link: https://lore.kernel.org/r/20220311020017.1509316-1-jiyong@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

vhost/vsock: don't check owner in vhost_vsock_stop() while releasing

2022-03-02T10:42:46+00:00

commit a58da53ffd70294ebea8ecd0eb45fd0d74add9f9 upstream. vhost_vsock_stop() calls vhost_dev_check_owner() to check the device ownership. It expects current->mm to be valid. vhost_vsock_stop() is also called by vhost_vsock_dev_release() when the user has not done close(), so when we are in do_exit(). In this case current->mm is invalid and we're releasing the device, so we should clean it anyway. Let's check the owner only when vhost_vsock_stop() is called by an ioctl. When invoked from release we can not fail so we don't check return code of vhost_vsock_stop(). We need to stop vsock even if it's not the owner. Fixes: 433fc58e6bf2 ("VSOCK: Introduce vhost_vsock.ko") Cc: stable@vger.kernel.org Reported-by: syzbot+1e3ea63db39f2b4440e0@syzkaller.appspotmail.com Reported-and-tested-by: syzbot+3140b17cb44a7b174008@syzkaller.appspotmail.com Signed-off-by: Stefano Garzarella Acked-by: Jason Wang Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

vhost/vsock: fix incorrect used length reported to the guest

2021-12-01T08:19:09+00:00

commit 49d8c5ffad07ca014cfae72a1b9b8c52b6ad9cb8 upstream. The "used length" reported by calling vhost_add_used() must be the number of bytes written by the device (using "in" buffers). In vhost_vsock_handle_tx_kick() the device only reads the guest buffers (they are all "out" buffers), without writing anything, so we must pass 0 as "used length" to comply virtio spec. Fixes: 433fc58e6bf2 ("VSOCK: Introduce vhost_vsock.ko") Cc: stable@vger.kernel.org Reported-by: Halil Pasic Suggested-by: Jason Wang Signed-off-by: Stefano Garzarella Link: https://lore.kernel.org/r/20211122163525.294024-2-sgarzare@redhat.com Signed-off-by: Michael S. Tsirkin Reviewed-by: Stefan Hajnoczi Reviewed-by: Halil Pasic Signed-off-by: Greg Kroah-Hartman

vhost: allow device that does not depend on vhost worker

2020-06-04T19:36:51+00:00

vDPA device currently relays the eventfd via vhost worker. This is inefficient due the latency of wakeup and scheduling, so this patch tries to introduce a use_worker attribute for the vhost device. When use_worker is not set with vhost_dev_init(), vhost won't try to allocate a worker thread and the vhost_poll will be processed directly in the wakeup function. This help for vDPA since it reduces the latency caused by vhost worker. In my testing, it saves 0.2 ms in pings between VMs on a mutual host. Signed-off-by: Zhu Lingshan Signed-off-by: Jason Wang Link: https://lore.kernel.org/r/20200529080303.15449-2-jasowang@redhat.com Signed-off-by: Michael S. Tsirkin

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2020-05-07T03:53:22+00:00

Pull networking fixes from David Miller: 1) Fix reference count leaks in various parts of batman-adv, from Xiyu Yang. 2) Update NAT checksum even when it is zero, from Guillaume Nault. 3) sk_psock reference count leak in tls code, also from Xiyu Yang. 4) Sanity check TCA_FQ_CODEL_DROP_BATCH_SIZE netlink attribute in fq_codel, from Eric Dumazet. 5) Fix panic in choke_reset(), also from Eric Dumazet. 6) Fix VLAN accel handling in bnxt_fix_features(), from Michael Chan. 7) Disallow out of range quantum values in sch_sfq, from Eric Dumazet. 8) Fix crash in x25_disconnect(), from Yue Haibing. 9) Don't pass pointer to local variable back to the caller in nf_osf_hdr_ctx_init(), from Arnd Bergmann. 10) Wireguard should use the ECN decap helper functions, from Toke Høiland-Jørgensen. 11) Fix command entry leak in mlx5 driver, from Moshe Shemesh. 12) Fix uninitialized variable access in mptcp's subflow_syn_recv_sock(), from Paolo Abeni. 13) Fix unnecessary out-of-order ingress frame ordering in macsec, from Scott Dial. 14) IPv6 needs to use a global serial number for dst validation just like ipv4, from David Ahern. 15) Fix up PTP_1588_CLOCK deps, from Clay McClure. 16) Missing NLM_F_MULTI flag in gtp driver netlink messages, from Yoshiyuki Kurauchi. 17) Fix a regression in that dsa user port errors should not be fatal, from Florian Fainelli. 18) Fix iomap leak in enetc driver, from Dejin Zheng. 19) Fix use after free in lec_arp_clear_vccs(), from Cong Wang. 20) Initialize protocol value earlier in neigh code paths when generating events, from Roman Mashak. 21) netdev_update_features() must be called with RTNL mutex in macsec driver, from Antoine Tenart. 22) Validate untrusted GSO packets even more strictly, from Willem de Bruijn. 23) Wireguard decrypt worker needs a cond_resched(), from Jason Donenfeld. * git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (111 commits) net: flow_offload: skip hw stats check for FLOW_ACTION_HW_STATS_DONT_CARE MAINTAINERS: put DYNAMIC INTERRUPT MODERATION in proper order wireguard: send/receive: use explicit unlikely branch instead of implicit coalescing wireguard: selftests: initalize ipv6 members to NULL to squelch clang warning wireguard: send/receive: cond_resched() when processing worker ringbuffers wireguard: socket: remove errant restriction on looping to self wireguard: selftests: use normal kernel stack size on ppc64 net: ethernet: ti: am65-cpsw-nuss: fix irqs type ionic: Use debugfs_create_bool() to export bool net: dsa: Do not leave DSA master with NULL netdev_ops net: dsa: remove duplicate assignment in dsa_slave_add_cls_matchall_mirred net: stricter validation of untrusted gso packets seg6: fix SRH processing to comply with RFC8754 net: mscc: ocelot: ANA_AUTOAGE_AGE_PERIOD holds a value in seconds, not ms net: dsa: ocelot: the MAC table on Felix is twice as large net: dsa: sja1105: the PTP_CLK extts input reacts on both edges selftests: net: tcp_mmap: fix SO_RCVLOWAT setting net: hsr: fix incorrect type usage for protocol variable net: macsec: fix rtnl locking issue net: mvpp2: cls: Prevent buffer overflow in mvpp2_ethtool_cls_rule_del() ...

vhost: vsock: kick send_pkt worker once device is started

2020-05-02T14:28:21+00:00

Ning Bo reported an abnormal 2-second gap when booting Kata container [1]. The unconditional timeout was caused by VSOCK_DEFAULT_CONNECT_TIMEOUT of connecting from the client side. The vhost vsock client tries to connect an initializing virtio vsock server. The abnormal flow looks like: host-userspace vhost vsock guest vsock ============== =========== ============ connect() --------> vhost_transport_send_pkt_work() initializing | vq->private_data==NULL | will not be queued V schedule_timeout(2s) vhost_vsock_start() <--------- device ready set vq->private_data wait for 2s and failed connect() again vq->private_data!=NULL recv connecting pkt Details: 1. Host userspace sends a connect pkt, at that time, guest vsock is under initializing, hence the vhost_vsock_start has not been called. So vq->private_data==NULL, and the pkt is not been queued to send to guest 2. Then it sleeps for 2s 3. After guest vsock finishes initializing, vq->private_data is set 4. When host userspace wakes up after 2s, send connecting pkt again, everything is fine. As suggested by Stefano Garzarella, this fixes it by additional kicking the send_pkt worker in vhost_vsock_start once the virtio device is started. This makes the pending pkt sent again. After this patch, kata-runtime (with vsock enabled) boot time is reduced from 3s to 1s on a ThunderX2 arm64 server. [1] https://github.com/kata-containers/runtime/issues/1917 Reported-by: Ning Bo Suggested-by: Stefano Garzarella Signed-off-by: Jia He Link: https://lore.kernel.org/r/20200501043840.186557-1-justin.he@arm.com Signed-off-by: Michael S. Tsirkin Reviewed-by: Stefano Garzarella

vsock/virtio: fix multiple packet delivery to monitoring devices

2020-04-27T17:18:01+00:00

In virtio_transport.c, if the virtqueue is full, the transmitting packet is queued up and it will be sent in the next iteration. This causes the same packet to be delivered multiple times to monitoring devices. We want to continue to deliver packets to monitoring devices before it is put in the virtqueue, to avoid that replies can appear in the packet capture before the transmitted packet. This patch fixes the issue, adding a new flag (tap_delivered) in struct virtio_vsock_pkt, to check if the packet is already delivered to monitoring devices. In vhost/vsock.c, we are splitting packets, so we must set 'tap_delivered' to false when we queue up the same virtio_vsock_pkt to handle the remaining bytes. Signed-off-by: Stefano Garzarella Signed-off-by: David S. Miller