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c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1761320446; 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=0gF93nT4QCSeQp0OqhTjXZ1wteCnmObHKQPrcwA+0mE=; b=aqp9Ns/R6cAcHnoYlaJ8MPC5QJBsshZ30WoyHLrmvtyf1D9HB/bxfymdjU/Y/F3KM0jM/C 0adcwunO/iw19hQt3vdFxCq292BF31nXAx71vXVxwD9hsKEX/Pf+7Is8pf6KtljELTbzQc hT8179pW5PntAaURD3Xw1zvzqawExnc= X-MC-Unique: PBuc54YQNoy69nhEst4WOA-1 X-Mimecast-MFC-AGG-ID: PBuc54YQNoy69nhEst4WOA_1761320443 From: =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= To: qemu-devel@nongnu.org Cc: Eduardo Habkost , =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= , Paolo Bonzini , Grant Millar | Cylo , Eric Blake Subject: [PULL 06/13] io: fix use after free in websocket handshake code Date: Fri, 24 Oct 2025 16:40:17 +0100 Message-ID: <20251024154024.227978-7-berrange@redhat.com> In-Reply-To: <20251024154024.227978-1-berrange@redhat.com> References: <20251024154024.227978-1-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 10.30.177.17 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: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, 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_H3=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: 1761320517057158500 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 CVE-2025-11234 Reported-by: Grant Millar | Cylo Reviewed-by: Eric Blake Signed-off-by: Daniel P. Berrang=C3=A9 --- include/io/channel-websock.h | 3 ++- io/channel-websock.c | 22 ++++++++++++++++------ 2 files changed, 18 insertions(+), 7 deletions(-) diff --git a/include/io/channel-websock.h b/include/io/channel-websock.h index e180827c57..6700cf8946 100644 --- a/include/io/channel-websock.h +++ b/include/io/channel-websock.h @@ -61,7 +61,8 @@ struct QIOChannelWebsock { size_t payload_remain; size_t pong_remain; QIOChannelWebsockMask mask; - guint io_tag; + guint hs_io_tag; /* tracking handshake task */ + guint io_tag; /* tracking watch task */ Error *io_err; gboolean io_eof; uint8_t opcode; diff --git a/io/channel-websock.c b/io/channel-websock.c index a50a160e18..cb4dafdebb 100644 --- a/io/channel-websock.c +++ b/io/channel-websock.c @@ -545,6 +545,7 @@ static gboolean qio_channel_websock_handshake_send(QIOC= hannel *ioc, trace_qio_channel_websock_handshake_fail(ioc, error_get_pretty(err= )); qio_task_set_error(task, err); qio_task_complete(task); + wioc->hs_io_tag =3D 0; return FALSE; } =20 @@ -560,6 +561,7 @@ static gboolean qio_channel_websock_handshake_send(QIOC= hannel *ioc, trace_qio_channel_websock_handshake_complete(ioc); qio_task_complete(task); } + wioc->hs_io_tag =3D 0; return FALSE; } trace_qio_channel_websock_handshake_pending(ioc, G_IO_OUT); @@ -586,6 +588,7 @@ static gboolean qio_channel_websock_handshake_io(QIOCha= nnel *ioc, trace_qio_channel_websock_handshake_fail(ioc, error_get_pretty(err= )); qio_task_set_error(task, err); qio_task_complete(task); + wioc->hs_io_tag =3D 0; return FALSE; } if (ret =3D=3D 0) { @@ -597,7 +600,7 @@ 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 +910,12 @@ 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 @@ -922,6 +926,9 @@ static void qio_channel_websock_finalize(Object *obj) buffer_free(&ioc->encinput); buffer_free(&ioc->encoutput); buffer_free(&ioc->rawinput); + if (ioc->hs_io_tag) { + g_source_remove(ioc->hs_io_tag); + } if (ioc->io_tag) { g_source_remove(ioc->io_tag); } @@ -1221,6 +1228,9 @@ 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