[PATCH net] tipc: force a dst refcount before doing decryption

[PATCH net] tipc: force a dst refcount before doing decryption

[Xin Long]

As it says in commit 3bc07321ccc2 ("xfrm: Force a dst refcount before
entering the xfrm type handlers"):

"Crypto requests might return asynchronous. In this case we leave the
 rcu protected region, so force a refcount on the skb's destination
 entry before we enter the xfrm type input/output handlers."

On TIPC decryption path it has the same problem, and skb_dst_force()
should be called before doing decryption to avoid a possible crash.

Shuang reported this issue when this warning is triggered:

  [] WARNING: include/net/dst.h:337 tipc_sk_rcv+0x1055/0x1ea0 [tipc]
  [] Kdump: loaded Tainted: G W --------- - - 4.18.0-496.el8.x86_64+debug
  [] Workqueue: crypto cryptd_queue_worker
  [] RIP: 0010:tipc_sk_rcv+0x1055/0x1ea0 [tipc]
  [] Call Trace:
  [] tipc_sk_mcast_rcv+0x548/0xea0 [tipc]
  [] tipc_rcv+0xcf5/0x1060 [tipc]
  [] tipc_aead_decrypt_done+0x215/0x2e0 [tipc]
  [] cryptd_aead_crypt+0xdb/0x190
  [] cryptd_queue_worker+0xed/0x190
  [] process_one_work+0x93d/0x17e0

Fixes: fc1b6d6de220 ("tipc: introduce TIPC encryption & authentication")
Reported-by: Shuang Li <shuali@redhat.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
---
 net/tipc/node.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/tipc/node.c b/net/tipc/node.c
index c1e890a82434..500320e5ca47 100644
--- a/net/tipc/node.c
+++ b/net/tipc/node.c
@@ -2105,6 +2105,7 @@ void tipc_rcv(struct net *net, struct sk_buff *skb, struct tipc_bearer *b)
 	} else {
 		n = tipc_node_find_by_id(net, ehdr->id);
 	}
+	skb_dst_force(skb);
 	tipc_crypto_rcv(net, (n) ? n->crypto_rx : NULL, &skb, b);
 	if (!skb)
 		return;
-- 
2.43.0

Re: [PATCH net] tipc: force a dst refcount before doing decryption

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Paolo Abeni <pabeni@redhat.com>:

On Sat, 15 Jun 2024 14:27:20 -0400 you wrote:
> As it says in commit 3bc07321ccc2 ("xfrm: Force a dst refcount before
> entering the xfrm type handlers"):
> 
> "Crypto requests might return asynchronous. In this case we leave the
>  rcu protected region, so force a refcount on the skb's destination
>  entry before we enter the xfrm type input/output handlers."
> 
> [...]

Here is the summary with links:
  - [net] tipc: force a dst refcount before doing decryption
    https://git.kernel.org/netdev/net/c/2ebe8f840c74

You are awesome, thank you!
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