On Mon, Oct 31, 2022 at 07:17:06PM -0700, Dexuan Cui wrote:
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 <[email protected]>
---

Changes in v2 (Thanks Stefano!):
 Fixed a typo in the commit message.
 Removed the unnecessary finish_wait() at the end of the loop.

LGTM:

Reviewed-by: Stefano Garzarella <[email protected]>


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) ||
--
2.25.1


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