From 2e0e4355b2d4edb66b7d8c198339e17940abd682 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= Date: Mon, 18 Mar 2024 13:03:19 +0000 Subject: [PATCH 2/3] Revert "chardev/char-socket: Fix TLS io channels sending too much data to the backend" MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit RH-Author: Daniel P. Berrangé RH-MergeRequest: 233: Fix handling of TLS sessions in chardevs RH-Jira: RHEL-24614 RH-Acked-by: Thomas Huth RH-Acked-by: Marc-André Lureau RH-Commit: [2/3] 1cb3d72b86ced0f70a09dfa0d325ae8a85db1b2b (berrange/centos-src-qemu) This commit results in unexpected termination of the TLS connection. When 'fd_can_read' returns 0, the code goes on to pass a zero length buffer to qio_channel_read. The TLS impl calls into gnutls_recv() with this zero length buffer, at which point GNUTLS returns an error GNUTLS_E_INVALID_REQUEST. This is treated as fatal by QEMU's TLS code resulting in the connection being torn down by the chardev. Simply skipping the qio_channel_read when the buffer length is zero is also not satisfactory, as it results in a high CPU burn busy loop massively slowing QEMU's functionality. The proper solution is to avoid tcp_chr_read being called at all unless the frontend is able to accept more data. This will be done in a followup commit. This reverts commit 462945cd22d2bcd233401ed3aa167d83a8e35b05 Reviewed-by: Thomas Huth Signed-off-by: Daniel P. Berrangé (cherry picked from commit e8ee827ffdb86ebbd5f5213a1f78123c25a90864) --- chardev/char-socket.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/chardev/char-socket.c b/chardev/char-socket.c index f48d341ebc..51d0943fce 100644 --- a/chardev/char-socket.c +++ b/chardev/char-socket.c @@ -492,9 +492,9 @@ static gboolean tcp_chr_read(QIOChannel *chan, GIOCondition cond, void *opaque) s->max_size <= 0) { return TRUE; } - len = tcp_chr_read_poll(opaque); - if (len > sizeof(buf)) { - len = sizeof(buf); + len = sizeof(buf); + if (len > s->max_size) { + len = s->max_size; } size = tcp_chr_recv(chr, (void *)buf, len); if (size == 0 || (size == -1 && errno != EAGAIN)) { -- 2.39.3