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[2604:1380:45e3:2400::1]) by mx.google.com with ESMTPS id a185-20020a6390c2000000b005cddfe0c82bsi1626703pge.211.2024.02.17.07.04.16 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 17 Feb 2024 07:04:16 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel+bounces-69924-ouuuleilei=gmail.com@vger.kernel.org designates 2604:1380:45e3:2400::1 as permitted sender) client-ip=2604:1380:45e3:2400::1; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=k20201202 header.b=bsxF0O0z; arc=pass (i=1 dkim=pass dkdomain=kernel.org); spf=pass (google.com: domain of linux-kernel+bounces-69924-ouuuleilei=gmail.com@vger.kernel.org designates 2604:1380:45e3:2400::1 as permitted sender) smtp.mailfrom="linux-kernel+bounces-69924-ouuuleilei=gmail.com@vger.kernel.org"; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: from smtp.subspace.kernel.org (wormhole.subspace.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sv.mirrors.kernel.org (Postfix) with ESMTPS id 14F3828302F for ; Sat, 17 Feb 2024 15:04:16 +0000 (UTC) Received: from localhost.localdomain (localhost.localdomain [127.0.0.1]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 936367E0E3; Sat, 17 Feb 2024 15:03:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="bsxF0O0z" Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6C63F7C09F; Sat, 17 Feb 2024 15:03:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708182183; cv=none; b=GIwflB0TdwKhk8yOoNo2SLNTT10b67AwxUaaL+NJFDWzvMuGu7ZdY8mTpWFRhxmnUlN4sZsAg3LIkbv2GzoE/2zVl2BfVDRDJ1ifWBTp4nAXkqlpycZJ8dyzwq8lZf9TkOVpmqxIKNJnqHn6EfvUIO0XU7WCKG6w9LNpD+p6Szg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708182183; c=relaxed/simple; bh=7qfwQMTk/6XmuQTgWrrAU6QDNKvMnI+7NUmGueoQmuc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=DirQYFZe/HgTvG1zN55Dn0aNfUArbFbZN5FNSaedW3BzdD8n+KwgeDxURF23KsFJSs+KcLje4+Lr9eoUxYF0Hx1I05jRtlNsBsI3AZ9trD/5DzXbAT4XF1tCNK5cMoygTIOYq5z7DlVqsyKWPspmZCFZIFLFSD/AsKn30QQ05rA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bsxF0O0z; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 02076C433C7; Sat, 17 Feb 2024 15:03:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1708182183; bh=7qfwQMTk/6XmuQTgWrrAU6QDNKvMnI+7NUmGueoQmuc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bsxF0O0zWvPp505t1lswvS1c07/vMyEj6NoWQGyVmOanlWHTgZy+BXheaA1LpqFsK 0EOGVlB6+Di9XgzmDKXGhgICuKHjiyS6StSQM/iKM/sGiYqjrPqy58nroPER5ekRMJ ukkP8NVixapjyuC4ugenR6sCoqfLLmhTDNOMMn9M1VDKUa4mcZi8ihmX+5Y1opV6Ik cAlY6KX71aBxy8Juy5Al0MNjz9km7CAkvJjYa8BHjMsEVAAPe66JRSkhhApIMwI48C RfvbdwgLwUXJfb++tbEMIfG0AHo6XVwD7DgIkjQTI9ERYmkSr4oXtVy7IP2V8shnfc yxVs5lHpLMx5Q== Received: from johan by xi.lan with local (Exim 4.97.1) (envelope-from ) id 1rbMDW-000000001Vs-35SB; Sat, 17 Feb 2024 16:03:02 +0100 From: Johan Hovold To: Bjorn Andersson , Andrzej Hajda , Neil Armstrong , Robert Foss , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Daniel Vetter , Vinod Koul Cc: Jonas Karlman , Laurent Pinchart , Jernej Skrabec , Konrad Dybcio , Kishon Vijay Abraham I , Dmitry Baryshkov , Rob Clark , Abhinav Kumar , Kuogee Hsieh , freedreno@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-phy@lists.infradead.org, Johan Hovold , stable@vger.kernel.org Subject: [PATCH 3/6] soc: qcom: pmic_glink_altmode: fix drm bridge use-after-free Date: Sat, 17 Feb 2024 16:02:25 +0100 Message-ID: <20240217150228.5788-4-johan+linaro@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240217150228.5788-1-johan+linaro@kernel.org> References: <20240217150228.5788-1-johan+linaro@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1791158917789245069 X-GMAIL-MSGID: 1791158917789245069 A recent DRM series purporting to simplify support for "transparent bridges" and handling of probe deferrals ironically exposed a use-after-free issue on pmic_glink_altmode probe deferral. This has manifested itself as the display subsystem occasionally failing to initialise and NULL-pointer dereferences during boot of machines like the Lenovo ThinkPad X13s. Specifically, the dp-hpd bridge is currently registered before all resources have been acquired which means that it can also be deregistered on probe deferrals. In the meantime there is a race window where the new aux bridge driver (or PHY driver previously) may have looked up the dp-hpd bridge and stored a (non-reference-counted) pointer to the bridge which is about to be deallocated. When the display controller is later initialised, this triggers a use-after-free when attaching the bridges: dp -> aux -> dp-hpd (freed) which may, for example, result in the freed bridge failing to attach: [drm:drm_bridge_attach [drm]] *ERROR* failed to attach bridge /soc@0/phy@88eb000 to encoder TMDS-31: -16 or a NULL-pointer dereference: Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 ... Call trace: drm_bridge_attach+0x70/0x1a8 [drm] drm_aux_bridge_attach+0x24/0x38 [aux_bridge] drm_bridge_attach+0x80/0x1a8 [drm] dp_bridge_init+0xa8/0x15c [msm] msm_dp_modeset_init+0x28/0xc4 [msm] The DRM bridge implementation is clearly fragile and implicitly built on the assumption that bridges may never go away. In this case, the fix is to move the bridge registration in the pmic_glink_altmode driver to after all resources have been looked up. Incidentally, with the new dp-hpd bridge implementation, which registers child devices, this is also a requirement due to a long-standing issue in driver core that can otherwise lead to a probe deferral loop (see fbc35b45f9f6 ("Add documentation on meaning of -EPROBE_DEFER")). Fixes: 080b4e24852b ("soc: qcom: pmic_glink: Introduce altmode support") Fixes: 2bcca96abfbf ("soc: qcom: pmic-glink: switch to DRM_AUX_HPD_BRIDGE") Cc: stable@vger.kernel.org # 6.3 Cc: Bjorn Andersson Cc: Dmitry Baryshkov Signed-off-by: Johan Hovold Reviewed-by: Bjorn Andersson Reviewed-by: Dmitry Baryshkov --- drivers/soc/qcom/pmic_glink_altmode.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/drivers/soc/qcom/pmic_glink_altmode.c b/drivers/soc/qcom/pmic_glink_altmode.c index 5fcd0fdd2faa..b3808fc24c69 100644 --- a/drivers/soc/qcom/pmic_glink_altmode.c +++ b/drivers/soc/qcom/pmic_glink_altmode.c @@ -76,7 +76,7 @@ struct pmic_glink_altmode_port { struct work_struct work; - struct device *bridge; + struct auxiliary_device *bridge; enum typec_orientation orientation; u16 svid; @@ -230,7 +230,7 @@ static void pmic_glink_altmode_worker(struct work_struct *work) else pmic_glink_altmode_enable_usb(altmode, alt_port); - drm_aux_hpd_bridge_notify(alt_port->bridge, + drm_aux_hpd_bridge_notify(&alt_port->bridge->dev, alt_port->hpd_state ? connector_status_connected : connector_status_disconnected); @@ -454,7 +454,7 @@ static int pmic_glink_altmode_probe(struct auxiliary_device *adev, alt_port->index = port; INIT_WORK(&alt_port->work, pmic_glink_altmode_worker); - alt_port->bridge = drm_dp_hpd_bridge_register(dev, to_of_node(fwnode)); + alt_port->bridge = devm_drm_dp_hpd_bridge_alloc(dev, to_of_node(fwnode)); if (IS_ERR(alt_port->bridge)) { fwnode_handle_put(fwnode); return PTR_ERR(alt_port->bridge); @@ -510,6 +510,16 @@ static int pmic_glink_altmode_probe(struct auxiliary_device *adev, } } + for (port = 0; port < ARRAY_SIZE(altmode->ports); port++) { + alt_port = &altmode->ports[port]; + if (!alt_port->bridge) + continue; + + ret = devm_drm_dp_hpd_bridge_add(dev, alt_port->bridge); + if (ret) + return ret; + } + altmode->client = devm_pmic_glink_register_client(dev, altmode->owner_id, pmic_glink_altmode_callback,