7.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ilia Gavrilov [ Upstream commit 7c24a4e87e219072e5e106f6791146cbf3b056b3 ] During the closure of a datagram socket, the vmci_transport_recv_dgram_cb() function may be called, which will add the packets to the socket's backlog; then, after the receive queue is cleared, the __release_sock() function will move the packet back from the socket's backlog to the receive queue, which will lead to a memory leak. sock_close __sock_release __vsock_release // take ownership by user-space lock_sock_nested sock_set_flag(sk, SOCK_DEAD) vmci_transport_release vmci_dispatch_dgs vmci_datagram_invoke_guest_handler vmci_transport_recv_dgram_cb sk_receive_skb if (!sock_owned_by_user(sk)) [...] (!) else if sk_add_backlog() [...] (!) skb_queue_purge(&sk->sk_receive_queue) release_sock __release_sock // move all packets from the backlog // to the receive queue (!) sk_backlog_rcv vsock_queue_rcv_skb [...] __sock_queue_rcv_skb if (!sock_flag(sk, SOCK_DEAD)) // Since the socket is "dead", the function will not // be called sk->sk_data_ready(sk) sock_release_ownership(sk); sock_put Add a receive queue cleanup in the socket destructor to fix this. syzkaller report: unreferenced object 0xffff8880117bfb80 (size 240): comm "irq/56-vmw_vmci", pid 205, jiffies 4295064448 (age 73.992s) hex dump (first 32 bytes): 78 dc 26 1e 80 88 ff ff 78 dc 26 1e 80 88 ff ff x.&.....x.&..... 00 00 00 00 00 00 00 00 c0 da 26 1e 80 88 ff ff ..........&..... backtrace: [] __alloc_skb+0x287/0x330 net/core/skbuff.c:505 [] vmci_transport_recv_dgram_cb+0xbd/0x210 [vmw_vsock_vmci_transport] [] vmci_datagram_invoke_guest_handler+0x366/0x450 [vmw_vmci] [] vmci_dispatch_dgs+0x235/0x490 [vmw_vmci] [] vmci_interrupt+0x55/0x290 [vmw_vmci] [] irq_thread_fn+0x8b/0x1a0 kernel/irq/manage.c:1205 [] irq_thread+0x28e/0x530 kernel/irq/manage.c:1314 [] kthread+0x2e6/0x3a0 kernel/kthread.c:376 [] ret_from_fork+0x22/0x30 arch/x86/entry/entry_64.S:295 Found by InfoTeCS on behalf of Linux Verification Center (linuxtesting.org) with Syzkaller. Fixes: d021c344051a ("VSOCK: Introduce VM Sockets") Reviewed-by: Stefano Garzarella Signed-off-by: Ilia Gavrilov Link: https://patch.msgid.link/20261008144046.90853-1-Ilia.Gavrilov@infotecs.ru Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/vmw_vsock/af_vsock.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c index 4a1dfde8414f4..f271a095996c9 100644 --- a/net/vmw_vsock/af_vsock.c +++ b/net/vmw_vsock/af_vsock.c @@ -1021,6 +1021,8 @@ static void vsock_sk_destruct(struct sock *sk) { struct vsock_sock *vsk = vsock_sk(sk); + /* Socket buffers may remain in the queue in VMCI datagram mode */ + __skb_queue_purge(&sk->sk_receive_queue); /* Flush MSG_ZEROCOPY leftovers. */ __skb_queue_purge(&sk->sk_error_queue); -- 2.53.0