[PATCH net 1/5] net/smc: fix dangling sock under state SMC_APPFINCLOSEWAIT

D. Wythe
2023-10-11T07:33:39Z

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

Considering scenario:

smc_cdc_rx_handler_rwwi
__smc_release
sock_set_flag
smc_close_active()
sock_set_flag

__set_bit(DEAD) __set_bit(DONE)

Dues to __set_bit is not atomic, the DEAD or DONE might be lost.
if the DEAD flag lost, the state SMC_CLOSED will be never be reached
in smc_close_passive_work:

if (sock_flag(sk, SOCK_DEAD) &&
smc_close_sent_any_close(conn)) {
sk->sk_state = SMC_CLOSED;
} else {
/* just shutdown, but not yet closed locally */
sk->sk_state = SMC_APPFINCLOSEWAIT;
}

Replace sock_set_flags or __set_bit to set_bit will fix this problem.
Since set_bit is atomic.

Signed-off-by: D. Wythe <alibuda@linux.alibaba.com>
---
net/smc/af_smc.c | 4 ++--
net/smc/smc.h | 5 +++++
net/smc/smc_cdc.c | 2 +-
net/smc/smc_close.c | 2 +-
4 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index bacdd97..5ad2a9f 100644
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -275,7 +275,7 @@ static int __smc_release(struct smc_sock *smc)

if (!smc->use_fallback) {
rc = smc_close_active(smc);
- sock_set_flag(sk, SOCK_DEAD);
+ smc_sock_set_flag(sk, SOCK_DEAD);
sk->sk_shutdown |= SHUTDOWN_MASK;
} else {
if (sk->sk_state != SMC_CLOSED) {
@@ -1742,7 +1742,7 @@ static int smc_clcsock_accept(struct smc_sock *lsmc, struct smc_sock **new_smc)
if (new_clcsock)
sock_release(new_clcsock);
new_sk->sk_state = SMC_CLOSED;
- sock_set_flag(new_sk, SOCK_DEAD);
+ smc_sock_set_flag(new_sk, SOCK_DEAD);
sock_put(new_sk); /* final */
*new_smc = NULL;
goto out;
diff --git a/net/smc/smc.h b/net/smc/smc.h
index 24745fd..e377980 100644
--- a/net/smc/smc.h
+++ b/net/smc/smc.h
@@ -377,4 +377,9 @@ void smc_fill_gid_list(struct smc_link_group *lgr,
int smc_nl_enable_hs_limitation(struct sk_buff *skb, struct genl_info *info);
int smc_nl_disable_hs_limitation(struct sk_buff *skb, struct genl_info *info);

+static inline void smc_sock_set_flag(struct sock *sk, enum sock_flags flag)
+{
+ set_bit(flag, &sk->sk_flags);
+}
+
#endif /* __SMC_H */
diff --git a/net/smc/smc_cdc.c b/net/smc/smc_cdc.c
index 89105e9..01bdb79 100644
--- a/net/smc/smc_cdc.c
+++ b/net/smc/smc_cdc.c
@@ -385,7 +385,7 @@ static void smc_cdc_msg_recv_action(struct smc_sock *smc,
smc->sk.sk_shutdown |= RCV_SHUTDOWN;
if (smc->clcsock && smc->clcsock->sk)
smc->clcsock->sk->sk_shutdown |= RCV_SHUTDOWN;
- sock_set_flag(&smc->sk, SOCK_DONE);
+ smc_sock_set_flag(&smc->sk, SOCK_DONE);
sock_hold(&smc->sk); /* sock_put in close_work */
if (!queue_work(smc_close_wq, &conn->close_work))
sock_put(&smc->sk);
diff --git a/net/smc/smc_close.c b/net/smc/smc_close.c
index dbdf03e..449ef45 100644
--- a/net/smc/smc_close.c
+++ b/net/smc/smc_close.c
@@ -173,7 +173,7 @@ void smc_close_active_abort(struct smc_sock *smc)
break;
}

- sock_set_flag(sk, SOCK_DEAD);
+ smc_sock_set_flag(sk, SOCK_DEAD);
sk->sk_state_change(sk);

if (release_clcsock) {
--
1.8.3.1