kernel/linux.git/net/vmw_vsock, branch v6.6.141

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

2026-05-17T15:13:54+00:00

commit 5f344d809e015fba3709e5219428c00b8ac5d7df upstream. 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 [LL: Fixed conflict since this tree does not use the offset added by commit 0df7cd3c13e4 ("vsock/virtio/vhost: read data from non-linear skb")] Signed-off-by: Luigi Leonardi Signed-off-by: Greg Kroah-Hartman

vsock/virtio: fix accept queue count leak on transport mismatch

2026-05-17T15:13:54+00:00

commit 52bcb57a4e8a0865a76c587c2451906342ae1b2d upstream. virtio_transport_recv_listen() calls sk_acceptq_added() before vsock_assign_transport(). If vsock_assign_transport() fails or selects a different transport, the error path returns without calling sk_acceptq_removed(), permanently incrementing sk_ack_backlog. After approximately backlog+1 such failures, sk_acceptq_is_full() returns true, causing the listener to reject all new connections. Fix by moving sk_acceptq_added() to after the transport validation, matching the pattern used by vmci_transport and hyperv_transport. Fixes: c0cfa2d8a788 ("vsock: add multi-transports support") Signed-off-by: Dudu Lu Reviewed-by: Bobby Eshleman Reviewed-by: Luigi Leonardi Reviewed-by: Stefano Garzarella Acked-by: Michael S. Tsirkin Link: https://patch.msgid.link/20260413131409.19022-1-phx0fer@gmail.com Signed-off-by: Paolo Abeni Cc: Luigi Leonardi Signed-off-by: Greg Kroah-Hartman

vsock: fix buffer size clamping order

2026-05-17T15:13:54+00:00

commit d114bfdc9b76bf93b881e195b7ec957c14227bab upstream. In vsock_update_buffer_size(), the buffer size was being clamped to the maximum first, and then to the minimum. If a user sets a minimum buffer size larger than the maximum, the minimum check overrides the maximum check, inverting the constraint. This breaks the intended socket memory boundaries by allowing the vsk->buffer_size to grow beyond the configured vsk->buffer_max_size. Fix this by checking the minimum first, and then the maximum. This ensures the buffer size never exceeds the buffer_max_size. Fixes: b9f2b0ffde0c ("vsock: handle buffer_size sockopts in the core") Suggested-by: Stefano Garzarella Signed-off-by: Norbert Szetei Reviewed-by: Stefano Garzarella Link: https://patch.msgid.link/180118C5-8BCF-4A63-A305-4EE53A34AB9C@doyensec.com Signed-off-by: Jakub Kicinski Cc: Luigi Leonardi Signed-off-by: Greg Kroah-Hartman

hv_sock: fix ARM64 support

2026-05-17T15:13:40+00:00

commit b31681206e3f527970a7c7ed807fbf6a028fc25b upstream. 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 Signed-off-by: Greg Kroah-Hartman

vmw_vsock: bypass false-positive Wnonnull warning with gcc-16

2026-03-04T12:20:49+00:00

[ Upstream commit e25dbf561e03c0c5e36228e3b8b784392819ce85 ] The gcc-16.0.1 snapshot produces a false-positive warning that turns into a build failure with CONFIG_WERROR: In file included from arch/x86/include/asm/string.h:6, from net/vmw_vsock/vmci_transport.c:10: In function 'vmci_transport_packet_init', inlined from '__vmci_transport_send_control_pkt.constprop' at net/vmw_vsock/vmci_transport.c:198:2: arch/x86/include/asm/string_32.h:150:25: error: argument 2 null where non-null expected because argument 3 is nonzero [-Werror=nonnull] 150 | #define memcpy(t, f, n) __builtin_memcpy(t, f, n) | ^~~~~~~~~~~~~~~~~~~~~~~~~ net/vmw_vsock/vmci_transport.c:164:17: note: in expansion of macro 'memcpy' 164 | memcpy(&pkt->u.wait, wait, sizeof(pkt->u.wait)); | ^~~~~~ arch/x86/include/asm/string_32.h:150:25: note: in a call to built-in function '__builtin_memcpy' net/vmw_vsock/vmci_transport.c:164:17: note: in expansion of macro 'memcpy' 164 | memcpy(&pkt->u.wait, wait, sizeof(pkt->u.wait)); | ^~~~~~ This seems relatively harmless, and it so far the only instance of this warning I have found. The __vmci_transport_send_control_pkt function is called either with wait=NULL or with one of the type values that pass 'wait' into memcpy() here, but not from the same caller. Replacing the memcpy with a struct assignment is otherwise the same but avoids the warning. Signed-off-by: Arnd Bergmann Reviewed-by: Bobby Eshleman Reviewed-by: Stefano Garzarella Reviewed-by: Bryan Tan Link: https://patch.msgid.link/20260203163406.2636463-1-arnd@kernel.org Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

vsock/virtio: cap TX credit to local buffer size

2026-01-30T09:27:37+00:00

[ Upstream commit 8ee784fdf006cbe8739cfa093f54d326cbf54037 ] The virtio transports derives its TX credit directly from peer_buf_alloc, which is set from the remote endpoint's SO_VM_SOCKETS_BUFFER_SIZE value. On the host side this means that the amount of data we are willing to queue for a connection is scaled by a guest-chosen buffer size, rather than the host's own vsock configuration. A malicious guest can advertise a large buffer and read slowly, causing the host to allocate a correspondingly large amount of sk_buff memory. The same thing would happen in the guest with a malicious host, since virtio transports share the same code base. Introduce a small helper, virtio_transport_tx_buf_size(), that returns min(peer_buf_alloc, buf_alloc), and use it wherever we consume peer_buf_alloc. This ensures the effective TX window is bounded by both the peer's advertised buffer and our own buf_alloc (already clamped to buffer_max_size via SO_VM_SOCKETS_BUFFER_MAX_SIZE), so a remote peer cannot force the other to queue more data than allowed by its own vsock settings. On an unpatched Ubuntu 22.04 host (~64 GiB RAM), running a PoC with 32 guest vsock connections advertising 2 GiB each and reading slowly drove Slab/SUnreclaim from ~0.5 GiB to ~57 GiB; the system only recovered after killing the QEMU process. That said, if QEMU memory is limited with cgroups, the maximum memory used will be limited. With this patch applied: Before: MemFree: ~61.6 GiB Slab: ~142 MiB SUnreclaim: ~117 MiB After 32 high-credit connections: MemFree: ~61.5 GiB Slab: ~178 MiB SUnreclaim: ~152 MiB Only ~35 MiB increase in Slab/SUnreclaim, no host OOM, and the guest remains responsive. Compatibility with non-virtio transports: - VMCI uses the AF_VSOCK buffer knobs to size its queue pairs per socket based on the local vsk->buffer_* values; the remote side cannot enlarge those queues beyond what the local endpoint configured. - Hyper-V's vsock transport uses fixed-size VMBus ring buffers and an MTU bound; there is no peer-controlled credit field comparable to peer_buf_alloc, and the remote endpoint cannot drive in-flight kernel memory above those ring sizes. - The loopback path reuses virtio_transport_common.c, so it naturally follows the same semantics as the virtio transport. This change is limited to virtio_transport_common.c and thus affects virtio-vsock, vhost-vsock, and loopback, bringing them in line with the "remote window intersected with local policy" behaviour that VMCI and Hyper-V already effectively have. Fixes: 06a8fc78367d ("VSOCK: Introduce virtio_vsock_common.ko") Suggested-by: Stefano Garzarella Signed-off-by: Melbin K Mathew [Stefano: small adjustments after changing the previous patch] [Stefano: tweak the commit message] Signed-off-by: Stefano Garzarella Reviewed-by: Luigi Leonardi Link: https://patch.msgid.link/20260121093628.9941-4-sgarzare@redhat.com Acked-by: Michael S. Tsirkin Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

vsock/virtio: fix potential underflow in virtio_transport_get_credit()

2026-01-30T09:27:37+00:00

[ Upstream commit 3ef3d52a1a9860d094395c7a3e593f3aa26ff012 ] The credit calculation in virtio_transport_get_credit() uses unsigned arithmetic: ret = vvs->peer_buf_alloc - (vvs->tx_cnt - vvs->peer_fwd_cnt); If the peer shrinks its advertised buffer (peer_buf_alloc) while bytes are in flight, the subtraction can underflow and produce a large positive value, potentially allowing more data to be queued than the peer can handle. Reuse virtio_transport_has_space() which already handles this case and add a comment to make it clear why we are doing that. Fixes: 06a8fc78367d ("VSOCK: Introduce virtio_vsock_common.ko") Suggested-by: Stefano Garzarella Signed-off-by: Melbin K Mathew [Stefano: use virtio_transport_has_space() instead of duplicating the code] [Stefano: tweak the commit message] Signed-off-by: Stefano Garzarella Reviewed-by: Luigi Leonardi Link: https://patch.msgid.link/20260121093628.9941-2-sgarzare@redhat.com Acked-by: Michael S. Tsirkin Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

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

2025-12-01T10:41:49+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()

2025-10-29T13:07:03+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: Validate length in packet header before skb_put()

2025-08-28T14:28:36+00:00

commit 0dab92484474587b82e8e0455839eaf5ac7bf894 upstream. When receiving a vsock packet in the guest, only the virtqueue buffer size is validated prior to virtio_vsock_skb_rx_put(). Unfortunately, virtio_vsock_skb_rx_put() uses the length from the packet header as the length argument to skb_put(), potentially resulting in SKB overflow if the host has gone wonky. Validate the length as advertised by the packet header before calling virtio_vsock_skb_rx_put(). Cc: Fixes: 71dc9ec9ac7d ("virtio/vsock: replace virtio_vsock_pkt with sk_buff") Signed-off-by: Will Deacon Message-Id: <20250717090116.11987-3-will@kernel.org> Signed-off-by: Michael S. Tsirkin Reviewed-by: Stefano Garzarella Signed-off-by: Greg Kroah-Hartman