kernel/linux.git/net/vmw_vsock, branch v7.1-rc5

vsock/virtio: fix skb overhead accounting to preserve full buf_alloc

2026-05-21T11:14:01+00:00

After commit 059b7dbd20a6 ("vsock/virtio: fix potential unbounded skb queue"), virtio_transport_inc_rx_pkt() subtracts per-skb overhead from buf_alloc when checking whether a new packet fits. This reduces the effective receive buffer below what the user configured via SO_VM_SOCKETS_BUFFER_SIZE, causing legitimate data packets to be silently dropped and applications that rely on the full buffer size to deadlock. Also, the reduced space is not communicated to the remote peer, so its credit calculation accounts more credit than the receiver will actually accept, causing data loss (there is no retransmission). With this approach we currently have failures in tools/testing/vsock/vsock_test.c. Test 18 sometimes fails, while test 22 always fails in this way: 18 - SOCK_STREAM MSG_ZEROCOPY...hash mismatch 22 - SOCK_STREAM virtio credit update + SO_RCVLOWAT...send failed: Resource temporarily unavailable Fix by allowing at most `buf_alloc * 2` as the total budget for payload plus skb overhead in virtio_transport_inc_rx_pkt(), similar to how SO_RCVBUF is doubled to reserve space for sk_buff metadata. This preserves the full buf_alloc for payload under normal operation, while still bounding the skb queue growth. With this patch, all tests in tools/testing/vsock/vsock_test.c are now passing again. Fixes: 059b7dbd20a6 ("vsock/virtio: fix potential unbounded skb queue") Cc: stable@vger.kernel.org Signed-off-by: Stefano Garzarella Link: https://patch.msgid.link/20260518090656.134588-3-sgarzare@redhat.com Signed-off-by: Paolo Abeni

vsock/virtio: reset connection on receiving queue overflow

2026-05-21T11:14:01+00:00

When there is no more space to queue an incoming packet, the packet is silently dropped. This causes data loss without any notification to either peer, since there is no retransmission. Under normal circumstances, this should never happen. However, it could happen if the other peer doesn't respect the credit, or if the skb overhead, which we recently began to take into account with commit 059b7dbd20a6 ("vsock/virtio: fix potential unbounded skb queue"), is too high. Fix this by resetting the connection and setting the local socket error to ENOBUFS when virtio_transport_recv_enqueue() can no longer queue a packet, so both peers are explicitly notified of the failure rather than silently losing data. Fixes: ae6fcfbf5f03 ("vsock/virtio: discard packets if credit is not respected") Cc: stable@vger.kernel.org Signed-off-by: Stefano Garzarella Link: https://patch.msgid.link/20260518090656.134588-2-sgarzare@redhat.com Signed-off-by: Paolo Abeni

vsock/vmci: fix UAF when peer resets connection during handshake

2026-05-21T02:11:18+00:00

vmci_transport_recv_connecting_server() returned err = 0 for a peer RST in its default switch arm: err = pkt->type == VMCI_TRANSPORT_PACKET_TYPE_RST ? 0 : -EINVAL; That made vmci_transport_recv_listen() skip vsock_remove_pending(), leaving the pending socket on the listener's pending_links with sk_state = TCP_CLOSE while destroy: still dropped the explicit reference taken before schedule_delayed_work(). One second later vsock_pending_work() observed is_pending=true and performed full cleanup: vsock_remove_pending() then the two trailing sock_put(sk) calls -- the first reached refcount 0 and __sk_freed the socket, and the second wrote into the freed object: BUG: KASAN: slab-use-after-free in refcount_warn_saturate Write of size 4 at addr ffff88800b1cac80 by task kworker Workqueue: events vsock_pending_work Treat peer RST like any other unexpected packet type (err = -EINVAL). All destroy: arms now return err < 0, so vmci_transport_recv_listen() removes pending from pending_links synchronously and vsock_pending_work() takes the is_pending=false / !rejected branch, dropping only its own work reference. This also closes the multi-packet race Sashiko reported on v2: pending is removed from the list before any subsequent packet can find it. The pre-existing sk_acceptq_removed() gap on the err < 0 path of vmci_transport_recv_listen() that Sashiko also noted is not introduced or changed by this patch. Tested on lts-6.12.79 with KASAN: 52/100 unpatched -> 0/100 patched. Fixes: d021c344051a ("VSOCK: Introduce VM Sockets") Cc: stable@vger.kernel.org Signed-off-by: Minh Nguyen Acked-by: Bryan Tan Link: https://patch.msgid.link/20260519102310.237181-1-minhnguyen.080505@gmail.com Signed-off-by: Jakub Kicinski

vsock/virtio: fix zerocopy completion for multi-skb sends

2026-05-16T00:38:15+00:00

When a large message is fragmented into multiple skbs, the zerocopy uarg is only allocated and attached to the last skb in the loop. Non-final skbs carry pinned user pages with no completion tracking, so the kernel has no way to notify userspace when those pages are safe to reuse. If the loop breaks early the uarg is never allocated at all, leaking pinned pages with no completion notification. Fix this by following the approach used by TCP: allocate the zerocopy uarg (if not provided by the caller) before the send loop and attach it to every skb via skb_zcopy_set(), which takes a reference per skb. Each skb's completion properly decrements the refcount, and the notification only fires after the last skb is freed. On failure, if no data was sent, the uarg is cleanly aborted via net_zcopy_put_abort(). This issue was initially discovered by sashiko while reviewing commit 1cb36e252211 ("vsock/virtio: fix MSG_ZEROCOPY pinned-pages accounting") but was pre-existing. Fixes: 581512a6dc93 ("vsock/virtio: MSG_ZEROCOPY flag support") Closes: https://sashiko.dev/#/patchset/20260420132051.217589-1-sgarzare%40redhat.com Reported-by: Maher Azzouzi Signed-off-by: Stefano Garzarella Acked-by: Michael S. Tsirkin Acked-by: Arseniy Krasnov Link: https://patch.msgid.link/20260514092948.268720-1-sgarzare@redhat.com Signed-off-by: Jakub Kicinski

vsock/virtio: fix empty payload in tap skb for non-linear buffers

2026-05-12T10:52:15+00:00

For non-linear skbs, virtio_transport_build_skb() goes through virtio_transport_copy_nonlinear_skb() to copy the original payload in the new skb to be delivered to the vsockmon tap device. This manually initializes an iov_iter but does not set iov_iter.count. Since the iov_iter is zero-initialized, the copy length is zero and no payload is actually copied to the monitor interface, leaving data un-initialized. Fix this by removing the linear vs non-linear split and using skb_copy_datagram_iter() with iov_iter_kvec() for all cases, as vhost-vsock already does. This handles both linear and non-linear skbs, properly initializes the iov_iter, and removes the now unused virtio_transport_copy_nonlinear_skb(). While touching this code, let's also check the return value of skb_copy_datagram_iter(), even though it's unlikely to fail. Fixes: 4b0bf10eb077 ("vsock/virtio: non-linear skb handling for tap") Reported-by: Yiqi Sun Signed-off-by: Stefano Garzarella Reviewed-by: Bobby Eshleman Reviewed-by: Arseniy Krasnov Link: https://patch.msgid.link/20260508164411.261440-3-sgarzare@redhat.com Acked-by: Michael S. Tsirkin Signed-off-by: Paolo Abeni

vsock/virtio: fix length and offset in tap skb for split packets

2026-05-12T10:52:15+00:00

virtio_transport_build_skb() builds a new skb to be delivered to the vsockmon tap device. To build the new skb, it uses the original skb data length as payload length, but as the comment notes, the original packet stored in the skb may have been split in multiple packets, so we need to use the length in the header, which is correctly updated before the packet is delivered to the tap, and the offset for the data. This was also similar to what we did before commit 71dc9ec9ac7d ("virtio/vsock: replace virtio_vsock_pkt with sk_buff") where we probably missed something during the skb conversion. Also update the comment above, which was left stale by the skb conversion and still mentioned a buffer pointer that no longer exists. Fixes: 71dc9ec9ac7d ("virtio/vsock: replace virtio_vsock_pkt with sk_buff") Signed-off-by: Stefano Garzarella Reviewed-by: Bobby Eshleman Reviewed-by: Arseniy Krasnov Link: https://patch.msgid.link/20260508164411.261440-2-sgarzare@redhat.com Acked-by: Michael S. Tsirkin Signed-off-by: Paolo Abeni

vsock/virtio: fix potential unbounded skb queue

2026-05-05T02:12:37+00:00

virtio_transport_inc_rx_pkt() checks vvs->rx_bytes + len > vvs->buf_alloc. virtio_transport_recv_enqueue() skips coalescing for packets with VIRTIO_VSOCK_SEQ_EOM. If fed with packets with len == 0 and VIRTIO_VSOCK_SEQ_EOM, a very large number of packets can be queued because vvs->rx_bytes stays at 0. Fix this by estimating the skb metadata size: (Number of skbs in the queue) * SKB_TRUESIZE(0) Fixes: 077706165717 ("virtio/vsock: don't use skbuff state to account credit") Signed-off-by: Eric Dumazet Cc: Arseniy Krasnov Cc: Stefan Hajnoczi Cc: Stefano Garzarella Cc: "Michael S. Tsirkin" Cc: Jason Wang Cc: Xuan Zhuo Cc: "Eugenio Pérez" Cc: virtualization@lists.linux.dev Link: https://patch.msgid.link/20260430122653.554058-1-edumazet@google.com Signed-off-by: Jakub Kicinski

hv_sock: fix ARM64 support

2026-04-30T00:30:45+00:00

VMBUS ring buffers must be page aligned. Therefore, the current value of 24K presents a challenge on ARM64 kernels (with 64K pages). So, use VMBUS_RING_SIZE() to ensure they are always aligned and large enough to hold all of the relevant data. Cc: stable@vger.kernel.org Fixes: 77ffe33363c0 ("hv_sock: use HV_HYP_PAGE_SIZE for Hyper-V communication") Tested-by: Dexuan Cui Reviewed-by: Dexuan Cui Signed-off-by: Hamza Mahfooz Acked-by: Stefano Garzarella Link: https://patch.msgid.link/20260428125339.13963-1-hamzamahfooz@linux.microsoft.com Signed-off-by: Jakub Kicinski

hv_sock: Return -EIO for malformed/short packets

2026-04-23T17:53:16+00:00

Commit f63152958994 fixes a regression, however it fails to report an error for malformed/short packets -- normally we should never see such packets, but let's report an error for them just in case. Fixes: f63152958994 ("hv_sock: Report EOF instead of -EIO for FIN") Cc: stable@vger.kernel.org Signed-off-by: Dexuan Cui Acked-by: Stefano Garzarella Link: https://patch.msgid.link/20260423064811.1371749-1-decui@microsoft.com Signed-off-by: Jakub Kicinski

vsock/virtio: fix MSG_ZEROCOPY pinned-pages accounting

2026-04-23T11:03:21+00:00

virtio_transport_init_zcopy_skb() uses iter->count as the size argument for msg_zerocopy_realloc(), which in turn passes it to mm_account_pinned_pages() for RLIMIT_MEMLOCK accounting. However, this function is called after virtio_transport_fill_skb() has already consumed the iterator via __zerocopy_sg_from_iter(), so on the last skb, iter->count will be 0, skipping the RLIMIT_MEMLOCK enforcement. Pass pkt_len (the total bytes being sent) as an explicit parameter to virtio_transport_init_zcopy_skb() instead of reading the already-consumed iter->count. This matches TCP and UDP, which both call msg_zerocopy_realloc() with the original message size. Fixes: 581512a6dc93 ("vsock/virtio: MSG_ZEROCOPY flag support") Reported-by: Yiming Qian Signed-off-by: Stefano Garzarella Reviewed-by: Bobby Eshleman Link: https://patch.msgid.link/20260420132051.217589-1-sgarzare@redhat.com Signed-off-by: Paolo Abeni