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 02B6D606A31D for ; Fri, 30 Oct 2026 17:44:28 +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=3kHRBHZ5; dkim=pass (2048-bit key, unprotected) header.d=sntech.de header.i=@sntech.de header.a=rsa-sha256 header.s=gloria202408 header.b=U9kWFnfC 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=usSQk3gmkVPvTdjKUU6vUCEb73RASrZuENLTQo/CskA=; b=3kHRBHZ5caveEiiAi3GUMdzTcJ xb3n9PMi2Ph470calOYxvm4ynS98oyGHaogIbw3G+SS4fFJEQUAoqOgvcgP86/phTgUyxkUC2FO47 vaH6e6bAwiesvI1P3puls66bd0BDuT6YVXdYplXrg6N9Nd7jrRtwjt+zMeuy72rCs3b6IrSh75qoz CEymrODsRTOfCrt4rrZhBX9CulUm0/wdnDSnOrVwLPrK+8NzFF6QOd3tt+Z3atQZkEuG0F9S1uxz7 f51idX32FrNedDp/Dz4nAfgFqGghCoVZSYeQ5+BcCCIMeZvC+ctWuUCjGENMp9Xv2DPbAD9ATBGNb gmBM6CYQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.100.1 #2 (Red Hat Linux)) id 1xMqeL-0000000CGdu-03sz; Fri, 30 Oct 2026 17:44:21 +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 1xMqeI-0000000CGdI-1mOX; Fri, 30 Oct 2026 17:44:19 +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=usSQk3gmkVPvTdjKUU6vUCEb73RASrZuENLTQo/CskA=; b=U9kWFnfC3oQMbgDNWHcOQJ/NJT HfgLlU43wb+0bVziHK6qseWoW1WMNY9f8Yajz9bGzugJq2zGqk+5Zl/V7gMxjMMyR2ibJg2DM/cKq mFzfarqU1oKC/MKLL6HJdfJrlr9ls7aCcDDFy74PBnwrJJomtlNsDXUz13oWND07rvw4PsnCH04QP aYc/Td6PEoaEgs9zzYMyNlzWqaiAeywaleFvaOvv0NUvxO68TRI9g5PexamYMQFGhtIA9nmouBK2A hlhLO7I37xAuZou/gPdDekGMLTi100S6UetXWliTUUnG1AXLWeo3vVV6iXXbak+pKHorNBooaP+i1 QmeOqqOg==; 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 18:43:47 +0100 Message-ID: <1844578.vCJZsxu672@phil> In-Reply-To: <20261029-jh7110-clean-send-v6-2-759594e43acf@samsung.com> References: <20261029-jh7110-clean-send-v6-0-759594e43acf@samsung.com> <20261029-jh7110-clean-send-v6-2-759594e43acf@samsung.com> 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_104418_464062_EB3C8964 X-CRM114-Status: GOOD ( 20.47 ) 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 Donnerstag, 29. Oktober 2026, 08:53:36 Mitteleurop=C3=A4ische Normalzeit= 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/bridge/= inno-hdmi.c > index d7c33b92e2ddf4ced84d17304463f44be52270b8..d29832249b942dec84fb9d07a= 0b21ee751fc0486 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 *dev_= 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. > + */ > + if (hdmi->bridge.dev) > + drm_helper_hpd_irq_event(hdmi->bridge.dev); Reviewed-by: Heiko Stuebner Most other callers of drm_helper_hpd_irq_event() also do exactly this. Heiko