sws: fix potential OOB write

Found by Codex Security

Follow-up to 0aaebf62ec281286afb9e51f2a8088302463df3f

Closes #20988

diff --git a/tests/server/sws.c b/tests/server/sws.c
index c73a34c6a22b407c7401965fbd45445a2018a00b..cc7adaf0521f00f67514b80736717bb06a3bdd15 100644 (file)
--- a/tests/server/sws.c
+++ b/tests/server/sws.c
@@ -1127,7 +1127,7 @@ static int sws_get_request(curl_socket_t sock, struct sws_httprequest *req)
       logmsg("wait for websocket traffic");
       do {
         got = sread(sock, reqbuf + req->offset,
-                    sizeof(req->reqbuf) - req->offset);
+                    sizeof(req->reqbuf) - 1 - req->offset);
         if(got > 0) {
           req->offset += got;
           logmsg("Got %zu bytes from client", got);