From mboxrd@z Thu Jan 1 00:00:00 1970 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 A12DD4086A; Tue, 11 Nov 2025 00:55:32 +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=1762822533; cv=none; b=BsgjC/ZC+NJ/bg8S0OGAwYNAfN3yI1kNZRAuRbzVP7tB0v4znHbynDkUJ/kG797o4inybhzyDib17aS+kjBbmBKzwjk+qD1RALZPcg1SPBYMmbB+jfvq8A0P9/RV53YiCcmdX9tHtX2/nrwo469JQnBMHR1kl6pHrAEamdsYZDI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762822533; c=relaxed/simple; bh=xjCBFBCNWsusTBdUvRI8LkS5ucvS2f16SQ3Su/D3KC4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Fc2hnLTi/70V4QXkiue4zLPrj+SOXncenl3KE8fjH5yf02GdySZknWBluAuw+fFDsw6QQKZTEmuqqswXQNddvj1RN4PVddlyokCWOHO1jTBM4HRkK8jydLk3he9++KvwsBabD0GllJz6uPjp3VxIgnlalBNy/QAEDW5sQTXTQ/w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=rmz6hygY; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="rmz6hygY" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EE8FCC116B1; Tue, 11 Nov 2025 00:55:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1762822532; bh=xjCBFBCNWsusTBdUvRI8LkS5ucvS2f16SQ3Su/D3KC4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rmz6hygYrJ1xlI6NlA0G+sCTqYiVPU3DdyqLLhPYUf6QVic27/lhjUgRYWXJOjiXl Ynvm/M5J/TsJkvbzWCQEefduP1YEUWcT3v5wYwXjt4q+/PhyfwReCp6yXmb2sfpP9d q8DVp8jBJ1V8Hh2BteQtNV6Q9Lwrr7tg9iSFU1rQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Sjoerd Simons , Ma Ke , AngeloGioacchino Del Regno , Johan Hovold , Ritesh Raj Sarraf , CK Hu , Chun-Kuang Hu Subject: [PATCH 6.12 069/565] drm/mediatek: Fix device use-after-free on unbind Date: Tue, 11 Nov 2025 09:38:45 +0900 Message-ID: <20251111004528.502494715@linuxfoundation.org> X-Mailer: git-send-email 2.51.2 In-Reply-To: <20251111004526.816196597@linuxfoundation.org> References: <20251111004526.816196597@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Johan Hovold commit 926d002e6d7e2f1fd5c1b53cf6208153ee7d380d upstream. A recent change fixed device reference leaks when looking up drm platform device driver data during bind() but failed to remove a partial fix which had been added by commit 80805b62ea5b ("drm/mediatek: Fix kobject put for component sub-drivers"). This results in a reference imbalance on component bind() failures and on unbind() which could lead to a user-after-free. Make sure to only drop the references after retrieving the driver data by effectively reverting the previous partial fix. Note that holding a reference to a device does not prevent its driver data from going away so there is no point in keeping the reference. Fixes: 1f403699c40f ("drm/mediatek: Fix device/node reference count leaks in mtk_drm_get_all_drm_priv") Reported-by: Sjoerd Simons Closes: https://lore.kernel.org/r/20251003-mtk-drm-refcount-v1-1-3b3f2813b0db@collabora.com Cc: stable@vger.kernel.org Cc: Ma Ke Cc: AngeloGioacchino Del Regno Signed-off-by: Johan Hovold Reviewed-by: AngeloGioacchino Del Regno Reviewed-by: Sjoerd Simons Tested-by: Sjoerd Simons Tested-by: Ritesh Raj Sarraf Reviewed-by: CK Hu Link: https://patchwork.kernel.org/project/dri-devel/patch/20251006093937.27869-1-johan@kernel.org/ Signed-off-by: Chun-Kuang Hu Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/mediatek/mtk_drm_drv.c | 10 ---------- 1 file changed, 10 deletions(-) --- a/drivers/gpu/drm/mediatek/mtk_drm_drv.c +++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.c @@ -684,10 +684,6 @@ err_free: for (i = 0; i < private->data->mmsys_dev_num; i++) private->all_drm_private[i]->drm = NULL; err_put_dev: - for (i = 0; i < private->data->mmsys_dev_num; i++) { - /* For device_find_child in mtk_drm_get_all_priv() */ - put_device(private->all_drm_private[i]->dev); - } put_device(private->mutex_dev); return ret; } @@ -695,18 +691,12 @@ err_put_dev: static void mtk_drm_unbind(struct device *dev) { struct mtk_drm_private *private = dev_get_drvdata(dev); - int i; /* for multi mmsys dev, unregister drm dev in mmsys master */ if (private->drm_master) { drm_dev_unregister(private->drm); mtk_drm_kms_deinit(private->drm); drm_dev_put(private->drm); - - for (i = 0; i < private->data->mmsys_dev_num; i++) { - /* For device_find_child in mtk_drm_get_all_priv() */ - put_device(private->all_drm_private[i]->dev); - } put_device(private->mutex_dev); } private->mtk_drm_bound = false;