[PATCH 5.7 08/15] tipc: call rcu_read_lock() in tipc_aead_encrypt_done()

Greg Kroah-Hartman
2020-08-26T12:04:04Z

From: Xin Long <lucien.xin@gmail.com>

[ Upstream commit f6db9096416209474090d64d8284e7c16c3d8873 ]

b->media->send_msg() requires rcu_read_lock(), as we can see
elsewhere in tipc, tipc_bearer_xmit, tipc_bearer_xmit_skb
and tipc_bearer_bc_xmit().

Syzbot has reported this issue as:

net/tipc/bearer.c:466 suspicious rcu_dereference_check() usage!
Workqueue: cryptd cryptd_queue_worker
Call Trace:
tipc_l2_send_msg+0x354/0x420 net/tipc/bearer.c:466
tipc_aead_encrypt_done+0x204/0x3a0 net/tipc/crypto.c:761
cryptd_aead_crypt+0xe8/0x1d0 crypto/cryptd.c:739
cryptd_queue_worker+0x118/0x1b0 crypto/cryptd.c:181
process_one_work+0x94c/0x1670 kernel/workqueue.c:2269
worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
kthread+0x3b5/0x4a0 kernel/kthread.c:291
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293

So fix it by calling rcu_read_lock() in tipc_aead_encrypt_done()
for b->media->send_msg().

Fixes: fc1b6d6de220 ("tipc: introduce TIPC encryption & authentication")
Reported-by: syzbot+47bbc6b678d317cccbe0@syzkaller.appspotmail.com
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/tipc/crypto.c | 2 ++
1 file changed, 2 insertions(+)

--- a/net/tipc/crypto.c
+++ b/net/tipc/crypto.c
@@ -757,10 +757,12 @@ static void tipc_aead_encrypt_done(struc
switch (err) {
case 0:
this_cpu_inc(tx->stats->stat[STAT_ASYNC_OK]);
+ rcu_read_lock();
if (likely(test_bit(0, &b->up)))
b->media->send_msg(net, skb, b, &tx_ctx->dst);
else
kfree_skb(skb);
+ rcu_read_unlock();
break;
case -EINPROGRESS:
return;