From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C6439CCA468 for ; Tue, 30 Sep 2025 10:49:26 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1v3Xud-0001ty-9w; Tue, 30 Sep 2025 06:48:51 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1v3Xub-0001tH-5k for qemu-trivial@nongnu.org; Tue, 30 Sep 2025 06:48:49 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1v3XuS-0001AZ-P6 for qemu-trivial@nongnu.org; Tue, 30 Sep 2025 06:48:48 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1759229316; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=BMt8cZdbP9ADF0C5nwha38ZeffnBpnBXZWHK7GSxspg=; b=VNlow6559Fi7+m9s/V/gixKJj2FMH6IWF4sS1n9KS9s+t8ACCfpPey4oODUBhMvGy1B0cg bbBdPh7eSqXV6oTOhIwb5JbfnH3FsIZCH9Mq9R7llK5d7MiZpWWtaHdV+Dg5St0yMFl3vg ty8fxqMRwB5rURB+RftsG6czUqaqQwk= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-631-kJU5ZSZbPO2q0wqW19Fy7w-1; Tue, 30 Sep 2025 06:48:31 -0400 X-MC-Unique: kJU5ZSZbPO2q0wqW19Fy7w-1 X-Mimecast-MFC-AGG-ID: kJU5ZSZbPO2q0wqW19Fy7w_1759229310 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 17348180034F; Tue, 30 Sep 2025 10:48:30 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.102]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 375B5195608E; Tue, 30 Sep 2025 10:48:27 +0000 (UTC) Date: Tue, 30 Sep 2025 11:48:24 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: =?utf-8?Q?Marc-Andr=C3=A9?= Lureau Cc: Grant Millar | Cylo , qemu-devel@nongnu.org, qemu-trivial@nongnu.org Subject: Re: [PATCH] ui/vnc: Fix NULL pointer dereference in vnc_disconnect_start Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/2.2.14 (2025-02-20) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 Received-SPF: pass client-ip=170.10.129.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -25 X-Spam_score: -2.6 X-Spam_bar: -- X-Spam_report: (-2.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.513, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-trivial@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-trivial-bounces+qemu-trivial=archiver.kernel.org@nongnu.org Sender: qemu-trivial-bounces+qemu-trivial=archiver.kernel.org@nongnu.org On Tue, Sep 30, 2025 at 02:38:40PM +0400, Marc-André Lureau wrote: > Hi > > On Tue, Sep 30, 2025 at 1:59 PM Grant Millar | Cylo wrote: > > > > From 0d1c4ac000a66ef22b4a0cd0c4bedd840192096a Mon Sep 17 00:00:00 2001 > > From: Rid > > Date: Tue, 30 Sep 2025 10:23:58 +0100 > > Subject: [PATCH] ui/vnc: Fix NULL pointer dereference in vnc_disconnect_start > > > > When a WebSocket connection fails during the handshake, vs->ioc can be > > NULL when vnc_disconnect_start() is called, leading to a segmentation > > fault when qio_channel_close() tries to dereference it. > > > > This can be reproduced by sending incomplete HTTP requests to the > > WebSocket port: > > > > for i in {1..100}; do > > (echo -n "GET / HTTP/1.1" && sleep 0.05) | nc -w 1 & > > done > > > > I tried to reproduce without success. This loop sometimes needs to be run 3 or 4 or more times before it will trigger. > Could you provide a backtrace? With valgrind the problem shows up as: ==2523108== Invalid read of size 4 ==2523108== at 0x4054A24: vnc_disconnect_start (vnc.c:1296) ==2523108== by 0x4054A24: vnc_client_error (vnc.c:1392) ==2523108== by 0x4068A09: vncws_handshake_done (vnc-ws.c:105) ==2523108== by 0x44863B4: qio_task_complete (task.c:197) ==2523108== by 0x448343D: qio_channel_websock_handshake_io (channel-websock.c:588) ==2523108== by 0x6EDB862: UnknownInlinedFun (gmain.c:3398) ==2523108== by 0x6EDB862: g_main_context_dispatch_unlocked.lto_priv.0 (gmain.c:4249) ==2523108== by 0x6EDBAE4: g_main_context_dispatch (gmain.c:4237) ==2523108== by 0x45EC79F: glib_pollfds_poll (main-loop.c:287) ==2523108== by 0x45EC79F: os_host_main_loop_wait (main-loop.c:310) ==2523108== by 0x45EC79F: main_loop_wait (main-loop.c:589) ==2523108== by 0x423A56D: qemu_main_loop (runstate.c:835) ==2523108== by 0x454F300: qemu_default_main (main.c:37) ==2523108== by 0x73D6574: (below main) (libc_start_call_main.h:58) ==2523108== Address 0x57a6e0dc is 28 bytes inside a block of size 103,608 free'd ==2523108== at 0x5F2FE43: free (vg_replace_malloc.c:989) ==2523108== by 0x6EDC444: g_free (gmem.c:208) ==2523108== by 0x4053F23: vnc_update_client (vnc.c:1153) ==2523108== by 0x4053F23: vnc_refresh (vnc.c:3225) ==2523108== by 0x4042881: dpy_refresh (console.c:880) ==2523108== by 0x4042881: gui_update (console.c:90) ==2523108== by 0x45EFA1B: timerlist_run_timers.part.0 (qemu-timer.c:562) ==2523108== by 0x45EFC8F: timerlist_run_timers (qemu-timer.c:495) ==2523108== by 0x45EFC8F: qemu_clock_run_timers (qemu-timer.c:576) ==2523108== by 0x45EFC8F: qemu_clock_run_all_timers (qemu-timer.c:663) ==2523108== by 0x45EC765: main_loop_wait (main-loop.c:600) ==2523108== by 0x423A56D: qemu_main_loop (runstate.c:835) ==2523108== by 0x454F300: qemu_default_main (main.c:37) ==2523108== by 0x73D6574: (below main) (libc_start_call_main.h:58) ==2523108== Block was alloc'd at ==2523108== at 0x5F343F3: calloc (vg_replace_malloc.c:1675) ==2523108== by 0x6EE2F81: g_malloc0 (gmem.c:133) ==2523108== by 0x4057DA3: vnc_connect (vnc.c:3245) ==2523108== by 0x448591B: qio_net_listener_channel_func (net-listener.c:54) ==2523108== by 0x6EDB862: UnknownInlinedFun (gmain.c:3398) ==2523108== by 0x6EDB862: g_main_context_dispatch_unlocked.lto_priv.0 (gmain.c:4249) ==2523108== by 0x6EDBAE4: g_main_context_dispatch (gmain.c:4237) ==2523108== by 0x45EC79F: glib_pollfds_poll (main-loop.c:287) ==2523108== by 0x45EC79F: os_host_main_loop_wait (main-loop.c:310) ==2523108== by 0x45EC79F: main_loop_wait (main-loop.c:589) ==2523108== by 0x423A56D: qemu_main_loop (runstate.c:835) ==2523108== by 0x454F300: qemu_default_main (main.c:37) ==2523108== by 0x73D6574: (below main) (libc_start_call_main.h:58) ==2523108== I'm working on a fix for QIOChannelWebsock... This VNC change is wrong. > > > Add a NULL check before calling qio_channel_close() to prevent the crash. > > > > Signed-off-by: Rid > > Your mail is not properly formatted. git am fails. > https://www.qemu.org/docs/master/devel/submitting-a-patch.html > > > thanks > > > --- > > ui/vnc.c | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/ui/vnc.c b/ui/vnc.c > > index 77c823bf2e..1669ed1b80 100644 > > --- a/ui/vnc.c > > +++ b/ui/vnc.c > > @@ -1301,7 +1301,9 @@ static void vnc_disconnect_start(VncState *vs) > > g_source_remove(vs->ioc_tag); > > vs->ioc_tag = 0; > > } > > - qio_channel_close(vs->ioc, NULL); > > + if (vs->ioc) { > > + qio_channel_close(vs->ioc, NULL); > > + } > > vs->disconnecting = TRUE; > > } > > > > -- > > 2.39.5 > > > > > -- > Marc-André Lureau > With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|