kernel/git/stable/linux.git/net/vmw_vsock, branch linux-6.17.y

vsock: Ignore signal/timeout on connect() if already established

2025-12-01T10:46:00+00:00

[ Upstream commit 002541ef650b742a198e4be363881439bb9d86b4 ] During connect(), acting on a signal/timeout by disconnecting an already established socket leads to several issues: 1. connect() invoking vsock_transport_cancel_pkt() -> virtio_transport_purge_skbs() may race with sendmsg() invoking virtio_transport_get_credit(). This results in a permanently elevated `vvs->bytes_unsent`. Which, in turn, confuses the SOCK_LINGER handling. 2. connect() resetting a connected socket's state may race with socket being placed in a sockmap. A disconnected socket remaining in a sockmap breaks sockmap's assumptions. And gives rise to WARNs. 3. connect() transitioning SS_CONNECTED -> SS_UNCONNECTED allows for a transport change/drop after TCP_ESTABLISHED. Which poses a problem for any simultaneous sendmsg() or connect() and may result in a use-after-free/null-ptr-deref. Do not disconnect socket on signal/timeout. Keep the logic for unconnected sockets: they don't linger, can't be placed in a sockmap, are rejected by sendmsg(). [1]: https://lore.kernel.org/netdev/e07fd95c-9a38-4eea-9638-133e38c2ec9b@rbox.co/ [2]: https://lore.kernel.org/netdev/20250317-vsock-trans-signal-race-v4-0-fc8837f3f1d4@rbox.co/ [3]: https://lore.kernel.org/netdev/60f1b7db-3099-4f6a-875e-af9f6ef194f6@rbox.co/ Fixes: d021c344051a ("VSOCK: Introduce VM Sockets") Signed-off-by: Michal Luczaj Reviewed-by: Stefano Garzarella Link: https://patch.msgid.link/20251119-vsock-interrupted-connect-v2-1-70734cf1233f@rbox.co Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

vsock: fix lock inversion in vsock_assign_transport()

2025-10-29T13:10:23+00:00

commit f7c877e7535260cc7a21484c994e8ce7e8cb6780 upstream. Syzbot reported a potential lock inversion deadlock between vsock_register_mutex and sk_lock-AF_VSOCK when vsock_linger() is called. The issue was introduced by commit 687aa0c5581b ("vsock: Fix transport_* TOCTOU") which added vsock_register_mutex locking in vsock_assign_transport() around the transport->release() call, that can call vsock_linger(). vsock_assign_transport() can be called with sk_lock held. vsock_linger() calls sk_wait_event() that temporarily releases and re-acquires sk_lock. During this window, if another thread hold vsock_register_mutex while trying to acquire sk_lock, a circular dependency is created. Fix this by releasing vsock_register_mutex before calling transport->release() and vsock_deassign_transport(). This is safe because we don't need to hold vsock_register_mutex while releasing the old transport, and we ensure the new transport won't disappear by obtaining a module reference first via try_module_get(). Reported-by: syzbot+10e35716f8e4929681fa@syzkaller.appspotmail.com Tested-by: syzbot+10e35716f8e4929681fa@syzkaller.appspotmail.com Fixes: 687aa0c5581b ("vsock: Fix transport_* TOCTOU") Cc: mhal@rbox.co Cc: stable@vger.kernel.org Signed-off-by: Stefano Garzarella Link: https://patch.msgid.link/20251021121718.137668-1-sgarzare@redhat.com Signed-off-by: Paolo Abeni Signed-off-by: Greg Kroah-Hartman

vsock/virtio: Fix message iterator handling on transmit path

2025-08-22T00:49:19+00:00

Commit 6693731487a8 ("vsock/virtio: Allocate nonlinear SKBs for handling large transmit buffers") converted the virtio vsock transmit path to utilise nonlinear SKBs when handling large buffers. As part of this change, virtio_transport_fill_skb() was updated to call skb_copy_datagram_from_iter() instead of memcpy_from_msg() as the latter expects a single destination buffer and cannot handle nonlinear SKBs correctly. Unfortunately, during this conversion, I overlooked the error case when the copying function returns -EFAULT due to a fault on the input buffer in userspace. In this case, memcpy_from_msg() reverts the iterator to its initial state thanks to copy_from_iter_full() whereas skb_copy_datagram_from_iter() leaves the iterator partially advanced. This results in a WARN_ONCE() from the vsock code, which expects the iterator to stay in sync with the number of bytes transmitted so that virtio_transport_send_pkt_info() can return -EFAULT when it is called again: ------------[ cut here ]------------ 'send_pkt()' returns 0, but 65536 expected WARNING: CPU: 0 PID: 5503 at net/vmw_vsock/virtio_transport_common.c:428 virtio_transport_send_pkt_info+0xd11/0xf00 net/vmw_vsock/virtio_transport_common.c:426 Modules linked in: CPU: 0 UID: 0 PID: 5503 Comm: syz.0.17 Not tainted 6.16.0-syzkaller-12063-g37816488247d #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Call virtio_transport_fill_skb_full() to restore the previous iterator behaviour. Cc: Jason Wang Cc: Stefano Garzarella Fixes: 6693731487a8 ("vsock/virtio: Allocate nonlinear SKBs for handling large transmit buffers") Reported-by: syzbot+b4d960daf7a3c7c2b7b1@syzkaller.appspotmail.com Signed-off-by: Will Deacon Acked-by: Michael S. Tsirkin Reviewed-by: Stefan Hajnoczi Link: https://patch.msgid.link/20250818180355.29275-3-will@kernel.org Signed-off-by: Jakub Kicinski

vsock: Do not allow binding to VMADDR_PORT_ANY

2025-08-08T19:55:00+00:00

It is possible for a vsock to autobind to VMADDR_PORT_ANY. This can cause a use-after-free when a connection is made to the bound socket. The socket returned by accept() also has port VMADDR_PORT_ANY but is not on the list of unbound sockets. Binding it will result in an extra refcount decrement similar to the one fixed in fcdd2242c023 (vsock: Keep the binding until socket destruction). Modify the check in __vsock_bind_connectible() to also prevent binding to VMADDR_PORT_ANY. Fixes: d021c344051a ("VSOCK: Introduce VM Sockets") Reported-by: Budimir Markovic Signed-off-by: Budimir Markovic Reviewed-by: Stefano Garzarella Link: https://patch.msgid.link/20250807041811.678-1-markovicbudimir@gmail.com Signed-off-by: Jakub Kicinski

Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost

2025-08-01T21:17:48+00:00

Pull virtio updates from Michael Tsirkin: - vhost can now support legacy threading if enabled in Kconfig - vsock memory allocation strategies for large buffers have been improved, reducing pressure on kmalloc - vhost now supports the in-order feature. guest bits missed the merge window. - fixes, cleanups all over the place * tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost: (30 commits) vsock/virtio: Allocate nonlinear SKBs for handling large transmit buffers vsock/virtio: Rename virtio_vsock_skb_rx_put() vhost/vsock: Allocate nonlinear SKBs for handling large receive buffers vsock/virtio: Move SKB allocation lower-bound check to callers vsock/virtio: Rename virtio_vsock_alloc_skb() vsock/virtio: Resize receive buffers so that each SKB fits in a 4K page vsock/virtio: Move length check to callers of virtio_vsock_skb_rx_put() vsock/virtio: Validate length in packet header before skb_put() vhost/vsock: Avoid allocating arbitrarily-sized SKBs vhost_net: basic in_order support vhost: basic in order support vhost: fail early when __vhost_add_used() fails vhost: Reintroduce kthread API and add mode selection vdpa: Fix IDR memory leak in VDUSE module exit vdpa/mlx5: Fix release of uninitialized resources on error path vhost-scsi: Fix check for inline_sg_cnt exceeding preallocated limit virtio: virtio_dma_buf: fix missing parameter documentation vhost: Fix typos vhost: vringh: Remove unused functions vhost: vringh: Remove unused iotlb functions ...

vsock/virtio: Allocate nonlinear SKBs for handling large transmit buffers

2025-08-01T13:11:09+00:00

When transmitting a vsock packet, virtio_transport_send_pkt_info() calls virtio_transport_alloc_linear_skb() to allocate and fill SKBs with the transmit data. Unfortunately, these are always linear allocations and can therefore result in significant pressure on kmalloc() considering that the maximum packet size (VIRTIO_VSOCK_MAX_PKT_BUF_SIZE + VIRTIO_VSOCK_SKB_HEADROOM) is a little over 64KiB, resulting in a 128KiB allocation for each packet. Rework the vsock SKB allocation so that, for sizes with page order greater than PAGE_ALLOC_COSTLY_ORDER, a nonlinear SKB is allocated instead with the packet header in the SKB and the transmit data in the fragments. Note that this affects both the vhost and virtio transports. Reviewed-by: Stefano Garzarella Signed-off-by: Will Deacon Message-Id: <20250717090116.11987-10-will@kernel.org> Signed-off-by: Michael S. Tsirkin

vsock/virtio: Rename virtio_vsock_skb_rx_put()

2025-08-01T13:11:09+00:00

In preparation for using virtio_vsock_skb_rx_put() when populating SKBs on the vsock TX path, rename virtio_vsock_skb_rx_put() to virtio_vsock_skb_put(). No functional change. Reviewed-by: Stefano Garzarella Signed-off-by: Will Deacon Message-Id: <20250717090116.11987-9-will@kernel.org> Signed-off-by: Michael S. Tsirkin

vsock/virtio: Rename virtio_vsock_alloc_skb()

2025-08-01T13:11:09+00:00

In preparation for nonlinear allocations for large SKBs, rename virtio_vsock_alloc_skb() to virtio_vsock_alloc_linear_skb() to indicate that it returns linear SKBs unconditionally and switch all callers over to this new interface for now. No functional change. Reviewed-by: Stefano Garzarella Signed-off-by: Will Deacon Message-Id: <20250717090116.11987-6-will@kernel.org> Signed-off-by: Michael S. Tsirkin

vsock/virtio: Resize receive buffers so that each SKB fits in a 4K page

2025-08-01T13:11:09+00:00

When allocating receive buffers for the vsock virtio RX virtqueue, an SKB is allocated with a 4140 data payload (the 44-byte packet header + VIRTIO_VSOCK_DEFAULT_RX_BUF_SIZE). Even when factoring in the SKB overhead, the resulting 8KiB allocation thanks to the rounding in kmalloc_reserve() is wasteful (~3700 unusable bytes) and results in a higher-order page allocation on systems with 4KiB pages just for the sake of a few hundred bytes of packet data. Limit the vsock virtio RX buffers to 4KiB per SKB, resulting in much better memory utilisation and removing the need to allocate higher-order pages entirely. Reviewed-by: Stefano Garzarella Signed-off-by: Will Deacon Message-Id: <20250717090116.11987-5-will@kernel.org> Signed-off-by: Michael S. Tsirkin

vsock/virtio: Move length check to callers of virtio_vsock_skb_rx_put()

2025-08-01T13:11:09+00:00

virtio_vsock_skb_rx_put() only calls skb_put() if the length in the packet header is not zero even though skb_put() handles this case gracefully. Remove the functionally redundant check from virtio_vsock_skb_rx_put() and, on the assumption that this is a worthwhile optimisation for handling credit messages, augment the existing length checks in virtio_transport_rx_work() to elide the call for zero-length payloads. Since the callers all have the length, extend virtio_vsock_skb_rx_put() to take it as an additional parameter rather than fish it back out of the packet header. Note that the vhost code already has similar logic in vhost_vsock_alloc_skb(). Reviewed-by: Stefano Garzarella Signed-off-by: Will Deacon Message-Id: <20250717090116.11987-4-will@kernel.org> Signed-off-by: Michael S. Tsirkin