commit d9a130e1962c2a5352f33088c563f4248a102c48
Author: Willy Tarreau <w@1wt.eu>
Date:   Fri Aug 24 15:48:59 2018 +0200

    BUG/MEDIUM: mux_pt: dereference the connection with care in mux_pt_wake()
    
    mux_pt_wake() calls data->wake() which can return -1 indicating that the
    connection was just destroyed. We need to check for this condition and
    immediately exit in this case otherwise we dereference a just freed
    connection. Note that this mainly happens on idle connections between
    two HTTP requests. It can have random implications between requests as
    it may lead a wrong connection's polling to be re-enabled or disabled
    for example, especially with threads.
    
    This patch must be backported to 1.8.
    
    (cherry picked from commit ad7f0ad1c3c9c541a4c315b24d4500405d1383ee)
    Signed-off-by: Willy Tarreau <w@1wt.eu>

diff --git a/src/mux_pt.c b/src/mux_pt.c
index a68b9621..c43e30f2 100644
--- a/src/mux_pt.c
+++ b/src/mux_pt.c
@@ -51,6 +51,9 @@ static int mux_pt_wake(struct connection *conn)
 
 	ret = cs->data_cb->wake ? cs->data_cb->wake(cs) : 0;
 
+	if (ret < 0)
+		return ret;
+
 	/* If we had early data, and we're done with the handshake
 	 * then whe know the data are safe, and we can remove the flag.
 	 */