[PATCH net 4/5] net/smc: protect connection state transitions in listen work

D. Wythe
2023-10-11T07:33:40Z

From: "D. Wythe" <alibuda@linux.alibaba.com>

Consider the following scenario:

smc_close_passive_work
smc_listen_out_connected
lock_sock()
if (state == SMC_INIT)
if (state == SMC_INIT)
state = SMC_APPCLOSEWAIT1;
state = SMC_ACTIVE
release_sock()

This would cause the state machine of the connection to be corrupted.
Also, this issue can occur in smc_listen_out_err().

To solve this problem, we can protect the state transitions under
the lock of sock to avoid collision.

Fixes: 3b2dec2603d5 ("net/smc: restructure client and server code in af_smc")
Signed-off-by: D. Wythe <alibuda@linux.alibaba.com>
---
net/smc/af_smc.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index 5ad2a9f..3bb8265 100644
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -1926,8 +1926,10 @@ static void smc_listen_out_connected(struct smc_sock *new_smc)
{
struct sock *newsmcsk = &new_smc->sk;

+ lock_sock(newsmcsk);
if (newsmcsk->sk_state == SMC_INIT)
newsmcsk->sk_state = SMC_ACTIVE;
+ release_sock(newsmcsk);

smc_listen_out(new_smc);
}
@@ -1939,9 +1941,12 @@ static void smc_listen_out_err(struct smc_sock *new_smc)
struct net *net = sock_net(newsmcsk);

this_cpu_inc(net->smc.smc_stats->srv_hshake_err_cnt);
+
+ lock_sock(newsmcsk);
if (newsmcsk->sk_state == SMC_INIT)
sock_put(&new_smc->sk); /* passive closing */
newsmcsk->sk_state = SMC_CLOSED;
+ release_sock(newsmcsk);

smc_listen_out(new_smc);
}
--
1.8.3.1