This is a note to let you know that I've just added the patch titled
tipc: fix kernel panic when enabling bearer
to the 5.16-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tipc-fix-kernel-panic-when-enabling-bearer.patch
and it can be found in the queue-5.16 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 3da9cb46e51354fa5f6e4e26bd4c72d6703649ea
Author: Tung Nguyen <tung.q.nguyen@xxxxxxxxxxxxxx>
Date: Fri Mar 4 03:25:18 2022 +0000
tipc: fix kernel panic when enabling bearer
[ 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@xxxxxxxxxx>
Acked-by: Jon Maloy <jmaloy@xxxxxxxxxx>
Signed-off-by: Tung Nguyen <tung.q.nguyen@xxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
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;
