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 15CABCCA470 for ; Tue, 30 Sep 2025 11:32:31 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1v3YZq-0004dr-02; Tue, 30 Sep 2025 07:31:26 -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 1v3YZk-0004Zw-7L for qemu-devel@nongnu.org; Tue, 30 Sep 2025 07:31:20 -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 1v3YZb-0007ZP-KB for qemu-devel@nongnu.org; Tue, 30 Sep 2025 07:31:18 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1759231846; 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=L7UWBXoGxj4jmZyH2TqWRnhB/wrjTZt1zopdNfZ8FNo=; b=ZGfzYjauDbYuMfNiprwPpfT0tnMn+Gq0n2bPKq1IhY8n8S7iBMY1DyU4R3CqWX1JbgVQMm 70cAZ8SRQv81eYK1kYU+ch/OzjlnBiA3MId8HzEVOMvRdn44OsAp92ORdALYGri3a9/ObZ WO0lVyxZdirE1BS2Up08YsUiL8kSJM0= Received: from mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-671-oTzBGAhTNkCu5trgj2ekIQ-1; Tue, 30 Sep 2025 07:30:43 -0400 X-MC-Unique: oTzBGAhTNkCu5trgj2ekIQ-1 X-Mimecast-MFC-AGG-ID: oTzBGAhTNkCu5trgj2ekIQ_1759231842 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (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-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id E6D031955F2B; Tue, 30 Sep 2025 11:30:41 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.102]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 7EFB619560B4; Tue, 30 Sep 2025 11:30:40 +0000 (UTC) Date: Tue, 30 Sep 2025 12:30:37 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: =?utf-8?Q?Marc-Andr=C3=A9?= Lureau Cc: qemu-devel@nongnu.org, Grant Millar | Cylo Subject: Re: [PATCH 2/2] io: fix use after free in websocket handshake code Message-ID: References: <20250930110834.2551757-1-berrange@redhat.com> <20250930110834.2551757-3-berrange@redhat.com> 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 10.30.177.12 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: -24 X-Spam_score: -2.5 X-Spam_bar: -- X-Spam_report: (-2.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.445, 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_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@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-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Tue, Sep 30, 2025 at 03:26:30PM +0400, Marc-André Lureau wrote: > Hi > > On Tue, Sep 30, 2025 at 3:08 PM Daniel P. Berrangé wrote: > > > > If the QIOChannelWebsock object is freed while it is waiting to > > complete a handshake, a GSource is leaked. This can lead to the > > callback firing later on and triggering a use-after-free in the > > use of the channel. This was observed in the VNC server with the > > following trace from valgrind: > > > > ==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== > > > > The above can be reproduced by launching QEMU with > > > > $ qemu-system-x86_64 -vnc localhost:0,websocket=5700 > > > > and then repeatedly running: > > > > for i in {1..100}; do > > (echo -n "GET / HTTP/1.1" && sleep 0.05) | nc -w 1 localhost 5700 & > > done > > > > Reported-by: Grant Millar | Cylo > > Signed-off-by: Daniel P. Berrangé > > --- > > include/io/channel-websock.h | 1 + > > io/channel-websock.c | 16 ++++++++++------ > > 2 files changed, 11 insertions(+), 6 deletions(-) > > > > diff --git a/include/io/channel-websock.h b/include/io/channel-websock.h > > index e180827c57..d1e760e449 100644 > > --- a/include/io/channel-websock.h > > +++ b/include/io/channel-websock.h > > @@ -61,6 +61,7 @@ struct QIOChannelWebsock { > > size_t payload_remain; > > size_t pong_remain; > > QIOChannelWebsockMask mask; > > + guint hs_io_tag; > > guint io_tag; > > I think it's worth a comment on why it needs two tags, and how they > relate to each other. > > > Error *io_err; > > gboolean io_eof; > > diff --git a/io/channel-websock.c b/io/channel-websock.c > > index 56d53355d5..588c313dfb 100644 > > --- a/io/channel-websock.c > > +++ b/io/channel-websock.c > > @@ -597,7 +597,7 @@ static gboolean qio_channel_websock_handshake_io(QIOChannel *ioc, > > error_propagate(&wioc->io_err, err); > > > > trace_qio_channel_websock_handshake_reply(ioc); > > - qio_channel_add_watch( > > + wioc->hs_io_tag = qio_channel_add_watch( > > wioc->master, > > G_IO_OUT, > > qio_channel_websock_handshake_send, > > @@ -907,11 +907,12 @@ void qio_channel_websock_handshake(QIOChannelWebsock *ioc, > > > > trace_qio_channel_websock_handshake_start(ioc); > > trace_qio_channel_websock_handshake_pending(ioc, G_IO_IN); > > - qio_channel_add_watch(ioc->master, > > - G_IO_IN, > > - qio_channel_websock_handshake_io, > > - task, > > - NULL); > > + ioc->hs_io_tag = qio_channel_add_watch( > > + ioc->master, > > + G_IO_IN, > > + qio_channel_websock_handshake_io, > > + task, > > + NULL); > > There is still an untracked qio_channel_add_watch(). I suppose you > checked that, it could use a comment explaining why it's left. I don't see any untracked add_watch remaining ? (If you're just doing a grep, you'll miss the prior line context where it captures the return value) > > > } > > > > > > @@ -1212,6 +1213,9 @@ static int qio_channel_websock_close(QIOChannel *ioc, > > buffer_free(&wioc->encinput); > > buffer_free(&wioc->encoutput); > > buffer_free(&wioc->rawinput); > > + if (wioc->hs_io_tag) { > > + g_clear_handle_id(&wioc->hs_io_tag, g_source_remove); > > + } > > if (wioc->io_tag) { > > g_clear_handle_id(&wioc->io_tag, g_source_remove); > > } > > -- > > 2.50.1 > > > > > -- > 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 :|