From 466a85336fee6e3b35eb97b8405a28302fd25809 Mon Sep 17 00:00:00 2001
From: Dexuan Cui <decui@microsoft.com>
Date: Mon, 31 Oct 2022 19:17:06 -0700
Subject: [PATCH] vsock: fix possible infinite sleep in vsock_connectible_wait_data()
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Git-commit: 466a85336fee6e3b35eb97b8405a28302fd25809
Patch-mainline: v6.1-rc4
References: git-fixes

Currently vsock_connectible_has_data() may miss a wakeup operation
between vsock_connectible_has_data() == 0 and the prepare_to_wait().

Fix the race by adding the process to the wait queue before checking
vsock_connectible_has_data().

Fixes: b3f7fd54881b ("af_vsock: separate wait data loop")
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Reported-by: Frédéric Dalleau <frederic.dalleau@docker.com>
Tested-by: Frédéric Dalleau <frederic.dalleau@docker.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 net/vmw_vsock/af_vsock.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index d258fd43092e..884eca7f6743 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -1905,8 +1905,11 @@ static int vsock_connectible_wait_data(struct sock *sk,
 	err = 0;
 	transport = vsk->transport;
 
-	while ((data = vsock_connectible_has_data(vsk)) == 0) {
+	while (1) {
 		prepare_to_wait(sk_sleep(sk), wait, TASK_INTERRUPTIBLE);
+		data = vsock_connectible_has_data(vsk);
+		if (data != 0)
+			break;
 
 		if (sk->sk_err != 0 ||
 		    (sk->sk_shutdown & RCV_SHUTDOWN) ||
-- 
2.35.3