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dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=AmAJr0Zx DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1747347621; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=De0gjRa3T5YCe7yJyKnDVayes1vb36P+Z2zMRdyCnAA=; b=ykqL7LuWaSALMuZrIT+6GZIo/epzIP8eI81JVpXCLWKVYGnUxf+e9xRq7Lh9F/68vNoypj Fj5RsirI2ylbvB5XhABVUBOfz7K3pRCki8TOb5xu7VTP79p3zdnwEaXejXENkqUjX8dAMY kmnUwFtBDEDWDz5gtl3h0AuLfBDyPSI= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1747347621; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=De0gjRa3T5YCe7yJyKnDVayes1vb36P+Z2zMRdyCnAA=; b=AmAJr0ZxyZ2QU6ZOhCQ85g+1I3TCEgFZMf1mgP1HPQw7v5RgRzhj5ZWru6xjdu3JLfhDSs BPOJKAcH9KeyiDBg== From: Fabiano Rosas To: qemu-devel@nongnu.org Cc: marcandre.lureau@redhat.com, berrange@redhat.com, pbonzini@redhat.com Subject: [PATCH 1/4] chardev: Fix QIOChannel refcount Date: Thu, 15 May 2025 19:20:11 -0300 Message-Id: <20250515222014.4161-2-farosas@suse.de> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20250515222014.4161-1-farosas@suse.de> References: <20250515222014.4161-1-farosas@suse.de> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 98228218E0 X-Rspamd-Action: no action X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Spamd-Result: default: False [-3.01 / 50.00]; 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helo=smtp-out1.suse.de X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=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 @suse.de) X-ZM-MESSAGEID: 1747347730791116600 Content-Type: text/plain; charset="utf-8" The IOWatchPoll holds a reference to the iochannel while the "child" source (iwp->src) is removed from the context and freed. Freeing the source leads to the iochannel being also freed at qio_channel_fd_source_finalize(). Later, io_watch_poll_prepare() tries to create another source with the same iochannel and hits an use after free: =3D=3D8241=3D=3DERROR: AddressSanitizer: heap-use-after-free on address 0x5= 14000000040 READ of size 8 at 0x514000000040 thread T2 #0 0x561c2d272fcd in object_get_class ../qom/object.c:1043:17 #1 0x561c2d338f84 in QIO_CHANNEL_GET_CLASS include/io/channel.h:29:1 #2 0x561c2d33b26f in qio_channel_create_watch ../io/channel.c:388:30 #3 0x561c2d2f0993 in io_watch_poll_prepare ../chardev/char-io.c:65:20 ... 0x514000000040 is located 0 bytes inside of 392-byte region [0x514000000040= ,0x5140000001c8) freed by thread T2 here: #0 0x561c2d2319a5 in free #1 0x7fb2c0926638 in g_free #2 0x561c2d276507 in object_finalize ../qom/object.c:734:9 #3 0x561c2d271d0d in object_unref ../qom/object.c:1231:9 #4 0x561c2d32ef1d in qio_channel_fd_source_finalize ../io/channel-watc= h.c:95:5 #5 0x7fb2c091d124 in g_source_unref_internal ../glib/gmain.c:2298 #6 0x561c2d2f0b6c in io_watch_poll_prepare ../chardev/char-io.c:71:9 ... previously allocated by thread T3 (connect) here: #0 0x561c2d231c69 in malloc #1 0x7fb2c0926518 in g_malloc #2 0x561c2d27246e in object_new_with_type ../qom/object.c:767:15 #3 0x561c2d272530 in object_new ../qom/object.c:789:12 #4 0x561c2d320193 in qio_channel_socket_new ../io/channel-socket.c:64:= 31 #5 0x561c2d308013 in tcp_chr_connect_client_async ../chardev/char-sock= et.c:1181:12 #6 0x561c2d3002e7 in qmp_chardev_open_socket_client ../chardev/char-so= cket.c:1281:9 ... Fix the issue by incrementing the iochannel reference count when the IOWatchPoll takes a reference and decrementing when it is finalized. Signed-off-by: Fabiano Rosas Reviewed-by: Daniel P. Berrang=C3=A9 --- chardev/char-io.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/chardev/char-io.c b/chardev/char-io.c index 3be17b51ca..d9b11f335f 100644 --- a/chardev/char-io.c +++ b/chardev/char-io.c @@ -88,6 +88,9 @@ static gboolean io_watch_poll_dispatch(GSource *source, G= SourceFunc callback, static void io_watch_poll_finalize(GSource *source) { IOWatchPoll *iwp =3D io_watch_poll_from_source(source); + + object_unref(OBJECT(iwp->ioc)); + if (iwp->src) { g_source_destroy(iwp->src); g_source_unref(iwp->src); @@ -117,6 +120,8 @@ GSource *io_add_watch_poll(Chardev *chr, iwp->fd_can_read =3D fd_can_read; iwp->opaque =3D user_data; iwp->ioc =3D ioc; + object_ref(OBJECT(iwp->ioc)); + iwp->fd_read =3D (GSourceFunc) fd_read; iwp->src =3D NULL; iwp->context =3D context; --=20 2.35.3