4.4 KiB
CVE-2024-53168
Description
In the Linux kernel, the following vulnerability has been resolved:sunrpc: fix one UAF issue caused by sunrpc kernel tcp socketBUG: KASAN: slab-use-after-free in tcp_write_timer_handler+0x156/0x3e0Read of size 1 at addr ffff888111f322cd by task swapper/0/0CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.12.0-rc4-dirty #7Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1Call Trace: dump_stack_lvl+0x68/0xa0 print_address_description.constprop.0+0x2c/0x3d0 print_report+0xb4/0x270 kasan_report+0xbd/0xf0 tcp_write_timer_handler+0x156/0x3e0 tcp_write_timer+0x66/0x170 call_timer_fn+0xfb/0x1d0 __run_timers+0x3f8/0x480 run_timer_softirq+0x9b/0x100 handle_softirqs+0x153/0x390 __irq_exit_rcu+0x103/0x120 irq_exit_rcu+0xe/0x20 sysvec_apic_timer_interrupt+0x76/0x90 asm_sysvec_apic_timer_interrupt+0x1a/0x20RIP: 0010:default_idle+0xf/0x20Code: 4c 01 c7 4c 29 c2 e9 72 ff ff ff 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d 33 f8 25 00 fb f4 c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90RSP: 0018:ffffffffa2007e28 EFLAGS: 00000242RAX: 00000000000f3b31 RBX: 1ffffffff4400fc7 RCX: ffffffffa09c3196RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff9f00590fRBP: 0000000000000000 R08: 0000000000000001 R09: ffffed102360835dR10: ffff88811b041aeb R11: 0000000000000001 R12: 0000000000000000R13: ffffffffa202d7c0 R14: 0000000000000000 R15: 00000000000147d0 default_idle_call+0x6b/0xa0 cpuidle_idle_call+0x1af/0x1f0 do_idle+0xbc/0x130 cpu_startup_entry+0x33/0x40 rest_init+0x11f/0x210 start_kernel+0x39a/0x420 x86_64_start_reservations+0x18/0x30 x86_64_start_kernel+0x97/0xa0 common_startup_64+0x13e/0x141 Allocated by task 595: kasan_save_stack+0x24/0x50 kasan_save_track+0x14/0x30 __kasan_slab_alloc+0x87/0x90 kmem_cache_alloc_noprof+0x12b/0x3f0 copy_net_ns+0x94/0x380 create_new_namespaces+0x24c/0x500 unshare_nsproxy_namespaces+0x75/0xf0 ksys_unshare+0x24e/0x4f0 __x64_sys_unshare+0x1f/0x30 do_syscall_64+0x70/0x180 entry_SYSCALL_64_after_hwframe+0x76/0x7eFreed by task 100: kasan_save_stack+0x24/0x50 kasan_save_track+0x14/0x30 kasan_save_free_info+0x3b/0x60 __kasan_slab_free+0x54/0x70 kmem_cache_free+0x156/0x5d0 cleanup_net+0x5d3/0x670 process_one_work+0x776/0xa90 worker_thread+0x2e2/0x560 kthread+0x1a8/0x1f0 ret_from_fork+0x34/0x60 ret_from_fork_asm+0x1a/0x30Reproduction script:mkdir -p /mnt/nfssharemkdir -p /mnt/nfs/netns_1mkfs.ext4 /dev/sdbmount /dev/sdb /mnt/nfssharesystemctl restart nfs-serverchmod 777 /mnt/nfsshareexportfs -i -o rw,no_root_squash *:/mnt/nfsshareip netns add netns_1ip link add name veth_1_peer type veth peer veth_1ifconfig veth_1_peer 11.11.0.254 upip link set veth_1 netns netns_1ip netns exec netns_1 ifconfig veth_1 11.11.0.1ip netns exec netns_1 /root/iptables -A OUTPUT -d 11.11.0.254 -p tcp \ --tcp-flags FIN FIN -j DROP(note: In my environment, a DESTROY_CLIENTID operation is always sent immediately, breaking the nfs tcp connection.)ip netns exec netns_1 timeout -s 9 300 mount -t nfs -o proto=tcp,vers=4.1 \ 11.11.0.254:/mnt/nfsshare /mnt/nfs/netns_1ip netns del netns_1The reason here is that the tcp socket in netns_1 (nfs side) has beenshutdown and closed (done in xs_destroy), but the FIN message (with ack)is discarded, and the nfsd side keeps sending retransmission messages.As a result, when the tcp sock in netns_1 processes the received message,it sends the message (FIN message) in the sending queue, and the tcp timeris re-established. When the network namespace is deleted, the net structureaccessed by tcp's timer handler function causes problems.To fix this problem, let's hold netns refcnt for the tcp kernel socket asdone in other modules. This is an ugly hack which can easily be backportedto earlier kernels. A proper fix which cleans up the interfaces willfollow, but may not be so easy to backport.
POC
Reference
No PoCs from references.