CVE-2023-52885

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> SUNRPC: Fix UAF in svc_tcp_listen_data_ready()<br /> <br /> After the listener svc_sock is freed, and before invoking svc_tcp_accept()<br /> for the established child sock, there is a window that the newsock<br /> retaining a freed listener svc_sock in sk_user_data which cloning from<br /> parent. In the race window, if data is received on the newsock, we will<br /> observe use-after-free report in svc_tcp_listen_data_ready().<br /> <br /> Reproduce by two tasks:<br /> <br /> 1. while :; do rpc.nfsd 0 ; rpc.nfsd; done<br /> 2. while :; do echo "" | ncat -4 127.0.0.1 2049 ; done<br /> <br /> KASAN report:<br /> <br /> ==================================================================<br /> BUG: KASAN: slab-use-after-free in svc_tcp_listen_data_ready+0x1cf/0x1f0 [sunrpc]<br /> Read of size 8 at addr ffff888139d96228 by task nc/102553<br /> CPU: 7 PID: 102553 Comm: nc Not tainted 6.3.0+ #18<br /> Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 11/12/2020<br /> Call Trace:<br /> <br /> dump_stack_lvl+0x33/0x50<br /> print_address_description.constprop.0+0x27/0x310<br /> print_report+0x3e/0x70<br /> kasan_report+0xae/0xe0<br /> svc_tcp_listen_data_ready+0x1cf/0x1f0 [sunrpc]<br /> tcp_data_queue+0x9f4/0x20e0<br /> tcp_rcv_established+0x666/0x1f60<br /> tcp_v4_do_rcv+0x51c/0x850<br /> tcp_v4_rcv+0x23fc/0x2e80<br /> ip_protocol_deliver_rcu+0x62/0x300<br /> ip_local_deliver_finish+0x267/0x350<br /> ip_local_deliver+0x18b/0x2d0<br /> ip_rcv+0x2fb/0x370<br /> __netif_receive_skb_one_core+0x166/0x1b0<br /> process_backlog+0x24c/0x5e0<br /> __napi_poll+0xa2/0x500<br /> net_rx_action+0x854/0xc90<br /> __do_softirq+0x1bb/0x5de<br /> do_softirq+0xcb/0x100<br /> <br /> <br /> ...<br /> <br /> <br /> Allocated by task 102371:<br /> kasan_save_stack+0x1e/0x40<br /> kasan_set_track+0x21/0x30<br /> __kasan_kmalloc+0x7b/0x90<br /> svc_setup_socket+0x52/0x4f0 [sunrpc]<br /> svc_addsock+0x20d/0x400 [sunrpc]<br /> __write_ports_addfd+0x209/0x390 [nfsd]<br /> write_ports+0x239/0x2c0 [nfsd]<br /> nfsctl_transaction_write+0xac/0x110 [nfsd]<br /> vfs_write+0x1c3/0xae0<br /> ksys_write+0xed/0x1c0<br /> do_syscall_64+0x38/0x90<br /> entry_SYSCALL_64_after_hwframe+0x72/0xdc<br /> <br /> Freed by task 102551:<br /> kasan_save_stack+0x1e/0x40<br /> kasan_set_track+0x21/0x30<br /> kasan_save_free_info+0x2a/0x50<br /> __kasan_slab_free+0x106/0x190<br /> __kmem_cache_free+0x133/0x270<br /> svc_xprt_free+0x1e2/0x350 [sunrpc]<br /> svc_xprt_destroy_all+0x25a/0x440 [sunrpc]<br /> nfsd_put+0x125/0x240 [nfsd]<br /> nfsd_svc+0x2cb/0x3c0 [nfsd]<br /> write_threads+0x1ac/0x2a0 [nfsd]<br /> nfsctl_transaction_write+0xac/0x110 [nfsd]<br /> vfs_write+0x1c3/0xae0<br /> ksys_write+0xed/0x1c0<br /> do_syscall_64+0x38/0x90<br /> entry_SYSCALL_64_after_hwframe+0x72/0xdc<br /> <br /> Fix the UAF by simply doing nothing in svc_tcp_listen_data_ready()<br /> if state != TCP_LISTEN, that will avoid dereferencing svsk for all<br /> child socket.