From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BA6F9606A322 for ; Fri, 30 Oct 2026 17:45:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=1wvKf39O; dkim=pass (2048-bit key, unprotected) header.d=sntech.de header.i=@sntech.de header.a=rsa-sha256 header.s=gloria202408 header.b=McnVzDrA DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Type: Content-Transfer-Encoding:MIME-Version:References:In-Reply-To:Message-ID:Date :Subject:Cc:To:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Unsubscribe-Post:List-Owner; bh=6g5elUdeGVozBVRB/uIpu9t+eT/QLwJb6+mCEOi3sU0=; b=1wvKf39Omw6s59dqAg7YkczM5I 0D62+Yn1OF0eO6tibMLxuXkdMPmpHxNCkYVwqTRusE2rOD2xq3lQGdZ73iPi3Gi3GuwbJ7OsbBOz+ tx4Vo+Q7YdNao3gRC0V3Y/Ystb39HHTtGDwkO7i6RndvvoknDECbztEpfUqAgwUDgLp+fJHcj5Vd0 1KMPP8InHaC32lZO03lybHoM4lSg8iTzIHBuyEZVPpSQIj1koqAgiZEzDKWpcr2RwWeNlX3bRFVcp woUecqFfYdupWLGBzd8Yg6ZiKTofxfA2fRdu/dZn4UOxJgA+DPEWvAPLVdn43XnWMTblko0BB4MQ4 eoo+s9Hg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.100.1 #2 (Red Hat Linux)) id 1xMqf2-0000000CGrt-1wuP; Fri, 30 Oct 2026 17:45:04 +0000 Received: from gloria.sntech.de ([185.11.138.130]) by bombadil.infradead.org with esmtps (Exim 4.100.1 #2 (Red Hat Linux)) id 1xMqez-0000000CGql-39kT; Fri, 30 Oct 2026 17:45:02 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sntech.de; s=gloria202408; h=Content-Type:Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From:Reply-To; bh=6g5elUdeGVozBVRB/uIpu9t+eT/QLwJb6+mCEOi3sU0=; b=McnVzDrABheU2AO7yOCTA46Wnj OQAwr+mr7ut6IbkprUPAK3ZO73I8BNz6LgFRR0aLlWHWPdUxhqs+MyYI9QPusA0ppO9RpQAMByt+5 kyQi4QZP4qr+kz0nBCHCewJpFTEI6sDQeU3G5eEMsnuLEJk7VMmGugR6rq8fGrfIfJ9B3oBmvF6eP zELkXz7C+gAmcKlmoUwpzrhgc3kqCPOPrd9WUA4jiFVAN+rZtcCsCMBRn7kzFI1SitdZDm4XVeYaz 1U/XNHSlGHiXrIKUKIzzBzY7SNDRlbZHnKrkm6fsARi4ILdgUjZcpjAMO3zBbK/YAQAl2gCTDFylv RgxT8d+w==; From: Heiko Stuebner To: Neil Armstrong , Rob Herring , Krzysztof Kozlowski , Andrzej Hajda , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , Luca Ceresoli , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Philipp Zabel , Emil Renner Berthing , Hal Feng , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Dominique Belhachemi , Andy Yan , David Airlie , Simona Vetter , Yakir Yang , Dmitry Baryshkov , Michal Wilczynski , Conor Dooley , William Qiu , Xingyu Wu , Sandy Huang , Manivannan Sadhasivam , Michal Wilczynski Cc: devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org, linux-riscv@lists.infradead.org, Marek Szyprowski , Maud Spierings , Graham Markall , Icenowy Zheng , Chaoyi Chen , Joshua Peisach , Uwe =?UTF-8?B?S2xlaW5lLUvDtm5pZw==?= Subject: Re: [PATCH v6 02/18] drm/bridge: inno-hdmi: Don't dereference a NULL drm_device on hotplug Date: Fri, 30 Oct 2026 18:44:24 +0100 Message-ID: <2261991.3Lj2Plt8kZ@phil> In-Reply-To: <1844578.vCJZsxu672@phil> References: <20261029-jh7110-clean-send-v6-0-759594e43acf@samsung.com> <20261029-jh7110-clean-send-v6-2-759594e43acf@samsung.com> <1844578.vCJZsxu672@phil> X-Archived-By: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261030_104501_802253_C6D75D58 X-CRM114-Status: GOOD ( 24.81 ) X-Spam-Score: -2.1 (--) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" X-Spam-Status: No, score=-15.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 Am Freitag, 30. Oktober 2026, 18:43:47 Mitteleurop=C3=A4ische Normalzeit sc= hrieb Heiko Stuebner: > Am Donnerstag, 29. Oktober 2026, 08:53:36 Mitteleurop=C3=A4ische Normalze= it schrieb Michal Wilczynski: > > inno_hdmi_irq() passes hdmi->bridge.dev to drm_helper_hpd_irq_event(), > > which dereferences it in its first statement: > >=20 > > if (!dev->mode_config.poll_enabled) > >=20 > > bridge.dev is assigned only by drm_bridge_attach(), but inno_hdmi_bind() > > unmutes the hotplug interrupt in inno_hdmi_init_hw() and installs the > > handler well before it attaches the bridge: > >=20 > > inno_hdmi_init_hw(hdmi); /* unmutes hotplug */ > > devm_request_threaded_irq(...); /* handler goes live */ > > ... > > hdmi->bridge.ddc =3D inno_hdmi_i2c_adapter(hdmi); > > devm_drm_bridge_add(dev, &hdmi->bridge); > > drm_bridge_attach(...); /* bridge.dev set here */ > >=20 > > The bridge is allocated by devm_drm_bridge_alloc(), which kzalloc()s it, > > so bridge.dev is NULL for all of that window, and a hotplug event > > arriving in it enters drm_helper_hpd_irq_event(NULL). > >=20 > > Before the conversion to a bridge the ordering was safe: > > inno_hdmi_register() called drmm_connector_hdmi_init(), which set > > connector.dev, before the interrupt was requested. > >=20 > > Drop hotplug events that arrive before the bridge is attached. > >=20 > > Fixes: 969325a2597e ("drm/rockchip: inno-hdmi: Convert to drm bridge") > > Signed-off-by: Michal Wilczynski > > --- > > drivers/gpu/drm/bridge/inno-hdmi.c | 8 +++++++- > > 1 file changed, 7 insertions(+), 1 deletion(-) > >=20 > > diff --git a/drivers/gpu/drm/bridge/inno-hdmi.c b/drivers/gpu/drm/bridg= e/inno-hdmi.c > > index d7c33b92e2ddf4ced84d17304463f44be52270b8..d29832249b942dec84fb9d0= 7a0b21ee751fc0486 100644 > > --- a/drivers/gpu/drm/bridge/inno-hdmi.c > > +++ b/drivers/gpu/drm/bridge/inno-hdmi.c > > @@ -929,7 +929,13 @@ static irqreturn_t inno_hdmi_irq(int irq, void *de= v_id) > > { > > struct inno_hdmi *hdmi =3D dev_id; > > =20 > > - drm_helper_hpd_irq_event(hdmi->bridge.dev); > > + /* > > + * The interrupt is requested before the bridge is attached, and > > + * bridge.dev is only set by drm_bridge_attach(). Drop hotplug events > > + * that arrive before then rather than dereference a NULL drm_device. > > + */ nit: I don't think that huge comment is necessary for that > > + if (hdmi->bridge.dev) > > + drm_helper_hpd_irq_event(hdmi->bridge.dev); >=20 > Reviewed-by: Heiko Stuebner >=20 > Most other callers of drm_helper_hpd_irq_event() also do exactly this. >=20 >=20 > Heiko >=20