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tipc: fix kernel panic when enabling bearer

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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]  <IRQ>
[    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.

Fixes: 35c55c9877 ("tipc: add neighbor monitoring framework")
Reported-by: Shuang Li <shuali@redhat.com>
Acked-by: Jon Maloy <jmaloy@redhat.com>
Signed-off-by: Tung Nguyen <tung.q.nguyen@dektech.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Tung Nguyen 2022-03-04 03:25:18 +00:00 committed by David S. Miller
parent 0bf476fc36
commit be4977b847
1 changed files with 7 additions and 5 deletions
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12
net/tipc/bearer.c
View File

@ -352,16 +352,18 @@ static int tipc_enable_bearer(struct net *net, const char *name,
goto rejected;
}
/* Create monitoring data before accepting activate messages */
if (tipc_mon_create(net, bearer_id)) {
bearer_disable(net, b);
kfree_skb(skb);
return -ENOMEM;
}
test_and_set_bit_lock(0, &b->up);
rcu_assign_pointer(tn->bearer_list[bearer_id], b);
if (skb)
tipc_bearer_xmit_skb(net, bearer_id, skb, &b->bcast_addr);
if (tipc_mon_create(net, bearer_id)) {
bearer_disable(net, b);
return -ENOMEM;
}
pr_info("Enabled bearer <%s>, priority %u\n", name, prio);
return res;