From 78dafe1cf3afa02ed71084b350713b07e72a18fb Mon Sep 17 00:00:00 2001 From: Michal Luczaj Date: Mon, 10 Feb 2025 13:15:00 +0100 Subject: [PATCH 1/2] vsock: Orphan socket after transport release During socket release, sock_orphan() is called without considering that it sets sk->sk_wq to NULL. Later, if SO_LINGER is enabled, this leads to a null pointer dereferenced in virtio_transport_wait_close(). Orphan the socket only after transport release. Partially reverts the 'Fixes:' commit. KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f] lock_acquire+0x19e/0x500 _raw_spin_lock_irqsave+0x47/0x70 add_wait_queue+0x46/0x230 virtio_transport_release+0x4e7/0x7f0 __vsock_release+0xfd/0x490 vsock_release+0x90/0x120 __sock_release+0xa3/0x250 sock_close+0x14/0x20 __fput+0x35e/0xa90 __x64_sys_close+0x78/0xd0 do_syscall_64+0x93/0x1b0 entry_SYSCALL_64_after_hwframe+0x76/0x7e Reported-by: syzbot+9d55b199192a4be7d02c@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=9d55b199192a4be7d02c Fixes: fcdd2242c023 ("vsock: Keep the binding until socket destruction") Tested-by: Luigi Leonardi Reviewed-by: Luigi Leonardi Signed-off-by: Michal Luczaj Link: https://patch.msgid.link/20250210-vsock-linger-nullderef-v3-1-ef6244d02b54@rbox.co Signed-off-by: Jakub Kicinski --- net/vmw_vsock/af_vsock.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c index 075695173648..53a081d49d28 100644 --- a/net/vmw_vsock/af_vsock.c +++ b/net/vmw_vsock/af_vsock.c @@ -824,13 +824,19 @@ static void __vsock_release(struct sock *sk, int level) */ lock_sock_nested(sk, level); - sock_orphan(sk); + /* Indicate to vsock_remove_sock() that the socket is being released and + * can be removed from the bound_table. Unlike transport reassignment + * case, where the socket must remain bound despite vsock_remove_sock() + * being called from the transport release() callback. + */ + sock_set_flag(sk, SOCK_DEAD); if (vsk->transport) vsk->transport->release(vsk); else if (sock_type_connectible(sk->sk_type)) vsock_remove_sock(vsk); + sock_orphan(sk); sk->sk_shutdown = SHUTDOWN_MASK; skb_queue_purge(&sk->sk_receive_queue); From 440c9d488705366b00372ea7213af69827a6c7af Mon Sep 17 00:00:00 2001 From: Michal Luczaj Date: Mon, 10 Feb 2025 13:15:01 +0100 Subject: [PATCH 2/2] vsock/test: Add test for SO_LINGER null ptr deref Explicitly close() a TCP_ESTABLISHED (connectible) socket with SO_LINGER enabled. As for now, test does not verify if close() actually lingers. On an unpatched machine, may trigger a null pointer dereference. Tested-by: Luigi Leonardi Reviewed-by: Luigi Leonardi Reviewed-by: Stefano Garzarella Signed-off-by: Michal Luczaj Link: https://patch.msgid.link/20250210-vsock-linger-nullderef-v3-2-ef6244d02b54@rbox.co Signed-off-by: Jakub Kicinski --- tools/testing/vsock/vsock_test.c | 41 ++++++++++++++++++++++++++++++++ 1 file changed, 41 insertions(+) diff --git a/tools/testing/vsock/vsock_test.c b/tools/testing/vsock/vsock_test.c index dfff8b288265..d0f6d253ac72 100644 --- a/tools/testing/vsock/vsock_test.c +++ b/tools/testing/vsock/vsock_test.c @@ -1788,6 +1788,42 @@ static void test_stream_connect_retry_server(const struct test_opts *opts) close(fd); } +static void test_stream_linger_client(const struct test_opts *opts) +{ + struct linger optval = { + .l_onoff = 1, + .l_linger = 1 + }; + int fd; + + fd = vsock_stream_connect(opts->peer_cid, opts->peer_port); + if (fd < 0) { + perror("connect"); + exit(EXIT_FAILURE); + } + + if (setsockopt(fd, SOL_SOCKET, SO_LINGER, &optval, sizeof(optval))) { + perror("setsockopt(SO_LINGER)"); + exit(EXIT_FAILURE); + } + + close(fd); +} + +static void test_stream_linger_server(const struct test_opts *opts) +{ + int fd; + + fd = vsock_stream_accept(VMADDR_CID_ANY, opts->peer_port, NULL); + if (fd < 0) { + perror("accept"); + exit(EXIT_FAILURE); + } + + vsock_wait_remote_close(fd); + close(fd); +} + static struct test_case test_cases[] = { { .name = "SOCK_STREAM connection reset", @@ -1943,6 +1979,11 @@ static struct test_case test_cases[] = { .run_client = test_stream_connect_retry_client, .run_server = test_stream_connect_retry_server, }, + { + .name = "SOCK_STREAM SO_LINGER null-ptr-deref", + .run_client = test_stream_linger_client, + .run_server = test_stream_linger_server, + }, {}, };