CVE-2022-48865 Information

Description

In the Linux kernel the following vulnerability has been resolved:

tipc: fix kernel panic when enabling bearer

When enabling a bearer on a node a kernel panic is observed:

[ 4.498085] RIP: 0010:tipc_mon_prep+0x4e/0x130 [tipc] … [ 4.520030] Call Trace: [ 4.520689] [ 4.521236] tipc_link_build_proto_msg+0x375/0x750 [tipc] [ 4.522654] tipc_link_build_state_msg+0x48/0xc0 [tipc] [ 4.524034] __tipc_node_link_up+0xd7/0x290 [tipc] [ 4.525292] tipc_rcv+0x5da/0x730 [tipc] [ 4.526346] ? __netif_receive_skb_core+0xb7/0xfc0 [ 4.527601] tipc_l2_rcv_msg+0x5e/0x90 [tipc] [ 4.528737] __netif_receive_skb_list_core+0x20b/0x260 [ 4.530068] netif_receive_skb_list_internal+0x1bf/0x2e0 [ 4.531450] ? dev_gro_receive+0x4c2/0x680 [ 4.532512] napi_complete_done+0x6f/0x180 [ 4.533570] virtnet_poll+0x29c/0x42e [virtio_net] …

The node in question is receiving activate messages in another thread after changing bearer status to allow message sending/ receiving in current thread:

     thread 1           |              thread 2
     --------           |              --------
                        |

tipc_enable_bearer() | test_and_set_bit_lock() | tipc_bearer_xmit_skb() | | tipc_l2_rcv_msg() | tipc_rcv() | __tipc_node_link_up() | tipc_link_build_state_msg() | tipc_link_build_proto_msg() | tipc_mon_prep() |
| … | // null-pointer dereference | u16 gen = mon->dom_gen; | … |
// Not being executed yet | tipc_mon_create() | | … | // allocate | mon = kzalloc(); | … | |

Monitoring pointer in thread 2 is dereferenced before monitoring data is allocated in thread 1. This causes kernel panic.

This commit fixes it by allocating the monitoring data before enabling the bearer to receive messages.

Reference

https://git.kernel.org/stable/c/2de76d37d4a6dca9b96ea51da24d4290e6cfa1a5 https://git.kernel.org/stable/c/f96dc3adb9a97b8f3dfdb88796483491a3006b71 https://git.kernel.org/stable/c/f4f59fdbc748805b08c13dae14c01f0518c77c94 https://git.kernel.org/stable/c/be4977b847f5d5cedb64d50eaaf2218c3a55a3a3