linux-kernel - [PATCH 5.10 20/86] net/smc: Fix sock leak when release after smc

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Message-Id: <20220426081741.795071079@linuxfoundation.org>
Date:   Tue, 26 Apr 2022 10:20:48 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Tony Lu <tonylu@...ux.alibaba.com>,
        Karsten Graul <kgraul@...ux.ibm.com>,
        "David S. Miller" <davem@...emloft.net>,
        Sasha Levin <sashal@...nel.org>,
        syzbot+6e29a053eb165bd50de5@...kaller.appspotmail.com
Subject: [PATCH 5.10 20/86] net/smc: Fix sock leak when release after smc_shutdown()

From: Tony Lu <tonylu@...ux.alibaba.com>

[ Upstream commit 1a74e99323746353bba11562a2f2d0aa8102f402 ]

Since commit e5d5aadcf3cd ("net/smc: fix sk_refcnt underflow on linkdown
and fallback"), for a fallback connection, __smc_release() does not call
sock_put() if its state is already SMC_CLOSED.

When calling smc_shutdown() after falling back, its state is set to
SMC_CLOSED but does not call sock_put(), so this patch calls it.

Reported-and-tested-by: syzbot+6e29a053eb165bd50de5@...kaller.appspotmail.com
Fixes: e5d5aadcf3cd ("net/smc: fix sk_refcnt underflow on linkdown and fallback")
Signed-off-by: Tony Lu <tonylu@...ux.alibaba.com>
Acked-by: Karsten Graul <kgraul@...ux.ibm.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 net/smc/af_smc.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index 4f16d406ad8e..1b98f3241150 100644
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -2144,8 +2144,10 @@ static int smc_shutdown(struct socket *sock, int how)
 	if (smc->use_fallback) {
 		rc = kernel_sock_shutdown(smc->clcsock, how);
 		sk->sk_shutdown = smc->clcsock->sk->sk_shutdown;
-		if (sk->sk_shutdown == SHUTDOWN_MASK)
+		if (sk->sk_shutdown == SHUTDOWN_MASK) {
 			sk->sk_state = SMC_CLOSED;
+			sock_put(sk);
+		}
 		goto out;
 	}
 	switch (how) {
-- 
2.35.1