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c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1759230528; h=from:from: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=WJ004NYdXAyPlxQNdz1jcbvRzHTnf1+4agR11jcuXJ8=; b=NplDPOyrI5NpRk0N5vlcuHEXBD8uJtgzeXNbdN+wbFJDHEzF8JobURyayVBEFB+ayLCO2e ht4s87WLmJ3Og1r+hnR0LxW7NeFOELpuOIt387SB9H4twyb5gf06HTbsjdJ6yShEm3kBbg VgUbDO15/Bmqiu9EVtF5irvXVYaazgU= X-MC-Unique: 4ezfv-RbO2OD8yjd8vHCIg-1 X-Mimecast-MFC-AGG-ID: 4ezfv-RbO2OD8yjd8vHCIg_1759230522 From: =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= To: qemu-devel@nongnu.org Cc: =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= , Grant Millar | Cylo , =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= Subject: [PATCH 2/2] io: fix use after free in websocket handshake code Date: Tue, 30 Sep 2025 12:08:34 +0100 Message-ID: <20250930110834.2551757-3-berrange@redhat.com> In-Reply-To: <20250930110834.2551757-1-berrange@redhat.com> References: <20250930110834.2551757-1-berrange@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.133.124; 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_H5=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: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1759230629964116600 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: =3D=3D2523108=3D=3D Invalid read of size 4 =3D=3D2523108=3D=3D at 0x4054A24: vnc_disconnect_start (vnc.c:1296) =3D=3D2523108=3D=3D by 0x4054A24: vnc_client_error (vnc.c:1392) =3D=3D2523108=3D=3D by 0x4068A09: vncws_handshake_done (vnc-ws.c:105) =3D=3D2523108=3D=3D by 0x44863B4: qio_task_complete (task.c:197) =3D=3D2523108=3D=3D by 0x448343D: qio_channel_websock_handshake_io (chan= nel-websock.c:588) =3D=3D2523108=3D=3D by 0x6EDB862: UnknownInlinedFun (gmain.c:3398) =3D=3D2523108=3D=3D by 0x6EDB862: g_main_context_dispatch_unlocked.lto_p= riv.0 (gmain.c:4249) =3D=3D2523108=3D=3D by 0x6EDBAE4: g_main_context_dispatch (gmain.c:4237) =3D=3D2523108=3D=3D by 0x45EC79F: glib_pollfds_poll (main-loop.c:287) =3D=3D2523108=3D=3D by 0x45EC79F: os_host_main_loop_wait (main-loop.c:31= 0) =3D=3D2523108=3D=3D by 0x45EC79F: main_loop_wait (main-loop.c:589) =3D=3D2523108=3D=3D by 0x423A56D: qemu_main_loop (runstate.c:835) =3D=3D2523108=3D=3D by 0x454F300: qemu_default_main (main.c:37) =3D=3D2523108=3D=3D by 0x73D6574: (below main) (libc_start_call_main.h:5= 8) =3D=3D2523108=3D=3D Address 0x57a6e0dc is 28 bytes inside a block of size = 103,608 free'd =3D=3D2523108=3D=3D at 0x5F2FE43: free (vg_replace_malloc.c:989) =3D=3D2523108=3D=3D by 0x6EDC444: g_free (gmem.c:208) =3D=3D2523108=3D=3D by 0x4053F23: vnc_update_client (vnc.c:1153) =3D=3D2523108=3D=3D by 0x4053F23: vnc_refresh (vnc.c:3225) =3D=3D2523108=3D=3D by 0x4042881: dpy_refresh (console.c:880) =3D=3D2523108=3D=3D by 0x4042881: gui_update (console.c:90) =3D=3D2523108=3D=3D by 0x45EFA1B: timerlist_run_timers.part.0 (qemu-time= r.c:562) =3D=3D2523108=3D=3D by 0x45EFC8F: timerlist_run_timers (qemu-timer.c:495) =3D=3D2523108=3D=3D by 0x45EFC8F: qemu_clock_run_timers (qemu-timer.c:57= 6) =3D=3D2523108=3D=3D by 0x45EFC8F: qemu_clock_run_all_timers (qemu-timer.= c:663) =3D=3D2523108=3D=3D by 0x45EC765: main_loop_wait (main-loop.c:600) =3D=3D2523108=3D=3D by 0x423A56D: qemu_main_loop (runstate.c:835) =3D=3D2523108=3D=3D by 0x454F300: qemu_default_main (main.c:37) =3D=3D2523108=3D=3D by 0x73D6574: (below main) (libc_start_call_main.h:5= 8) =3D=3D2523108=3D=3D Block was alloc'd at =3D=3D2523108=3D=3D at 0x5F343F3: calloc (vg_replace_malloc.c:1675) =3D=3D2523108=3D=3D by 0x6EE2F81: g_malloc0 (gmem.c:133) =3D=3D2523108=3D=3D by 0x4057DA3: vnc_connect (vnc.c:3245) =3D=3D2523108=3D=3D by 0x448591B: qio_net_listener_channel_func (net-lis= tener.c:54) =3D=3D2523108=3D=3D by 0x6EDB862: UnknownInlinedFun (gmain.c:3398) =3D=3D2523108=3D=3D by 0x6EDB862: g_main_context_dispatch_unlocked.lto_p= riv.0 (gmain.c:4249) =3D=3D2523108=3D=3D by 0x6EDBAE4: g_main_context_dispatch (gmain.c:4237) =3D=3D2523108=3D=3D by 0x45EC79F: glib_pollfds_poll (main-loop.c:287) =3D=3D2523108=3D=3D by 0x45EC79F: os_host_main_loop_wait (main-loop.c:31= 0) =3D=3D2523108=3D=3D by 0x45EC79F: main_loop_wait (main-loop.c:589) =3D=3D2523108=3D=3D by 0x423A56D: qemu_main_loop (runstate.c:835) =3D=3D2523108=3D=3D by 0x454F300: qemu_default_main (main.c:37) =3D=3D2523108=3D=3D by 0x73D6574: (below main) (libc_start_call_main.h:5= 8) =3D=3D2523108=3D=3D The above can be reproduced by launching QEMU with $ qemu-system-x86_64 -vnc localhost:0,websocket=3D5700 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. Berrang=C3=A9 --- 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; 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(QIOCha= nnel *ioc, error_propagate(&wioc->io_err, err); =20 trace_qio_channel_websock_handshake_reply(ioc); - qio_channel_add_watch( + wioc->hs_io_tag =3D 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, =20 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 =3D qio_channel_add_watch( + ioc->master, + G_IO_IN, + qio_channel_websock_handshake_io, + task, + NULL); } =20 =20 @@ -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); } --=20 2.50.1