From: Mark Amirkan Commit 581302298524 ("mptcp: error out earlier on disconnect") made mptcp_recvmsg() stop when sk_wait_data() returns an error. The error is stored in err, but the function then jumps to a path which returns copied. When no data was copied, recvmsg() therefore returns zero and reports a false EOF. Store the result in copied, which is the value returned by the function. This also keeps the usual partial-read result when data was copied before the error. A recvmsg() blocked in one thread reproduces the issue when another thread disconnects the same MPTCP socket with connect(AF_UNSPEC). Before this change recvmsg() returns zero; afterwards it returns -EPIPE. Fixes: 581302298524 ("mptcp: error out earlier on disconnect") Cc: stable@vger.kernel.org Assisted-by: Symbolic Signed-off-by: Mark Amirkan --- net/mptcp/protocol.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 0098e28309..8dc25ef154 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -2459,7 +2459,7 @@ static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, mptcp_cleanup_rbuf(msk, copied); err = sk_wait_data(sk, &timeo, last); if (err < 0) { - err = copied ? : err; + copied = copied ? : err; goto out_err; } } --- base-commit: 78445023439506ebd83b86d40b1e428a3b309d4a change-id: 20260913-b4-send-mptcp-recv-error-ef0f898e05cc Best regards, -- Mark Amirkan