From: Tung Nguyen tung.q.nguyen@dektech.com.au
[ Upstream commit be4977b847f5d5cedb64d50eaaf2218c3a55a3a3 ]
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: 35c55c9877f8 ("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 Signed-off-by: Sasha Levin sashal@kernel.org --- net/tipc/bearer.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/net/tipc/bearer.c b/net/tipc/bearer.c index 60bc74b76adc..1cb5907d90d8 100644 --- a/net/tipc/bearer.c +++ b/net/tipc/bearer.c @@ -352,16 +352,18 @@ static int tipc_enable_bearer(struct net *net, const char *name, goto rejected; }
- 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); - + /* 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); + pr_info("Enabled bearer <%s>, priority %u\n", name, prio);
return res;