From patchwork Thu May 5 11:31:24 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Javier Martinez Canillas X-Patchwork-Id: 12839408 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BA93AC433FE for ; Thu, 5 May 2022 11:31:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240742AbiEELfW (ORCPT ); Thu, 5 May 2022 07:35:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35564 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1351993AbiEELfV (ORCPT ); Thu, 5 May 2022 07:35:21 -0400 Received: from us-smtp-delivery-74.mimecast.com (us-smtp-delivery-74.mimecast.com [170.10.133.74]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id C28A325C70 for ; Thu, 5 May 2022 04:31:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1651750301; h=from:from:reply-to:subject:subject: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=ncwUrPXa6D//xAE+gUKX4W9jlEJvsWNrctcaxVQSCb8=; b=Sw25yEomYGdfy2bhmc3ZIBgyH+keQoLz6Z6KY5RLndheY9V99sPT8fJ3oYIuRtr+q3pc+t TSCcX9kTAJ/JiVmVNG8f0d6pBCv1i93NQPKoA2wvIyTpxlVH016jZxUgPLAevjDWRnovL5 PLNjMhg3C08ZsTExcjKB8oE0z0b8As4= Received: from mail-wm1-f69.google.com (mail-wm1-f69.google.com [209.85.128.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-38-A6ffjPjdOW68Br5fQ2VA5w-1; Thu, 05 May 2022 07:31:39 -0400 X-MC-Unique: A6ffjPjdOW68Br5fQ2VA5w-1 Received: by mail-wm1-f69.google.com with SMTP id h6-20020a7bc926000000b0039470bcb9easo142198wml.1 for ; Thu, 05 May 2022 04:31:39 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=ncwUrPXa6D//xAE+gUKX4W9jlEJvsWNrctcaxVQSCb8=; b=HBG8AJkAtRoHlGpbInpLxxUrQ8m5tybTtJuF4yd39nATYsQZ9aIUqYHcKKv48/TCxF Nj4RgbyXKtNaZf6v740ZQHQTzl0nItionmdibqUgW6ljgdcLI1VNrRugwkUWqlk1WYjL eKFHX+6zqOUXBPMyPLSbMquwc7VY0BoEbPhZ/7pFdKehsXpU61fwujtRNt+CYo2xPZ1l fNMslXIZyM4mSXcvr72wc0LiMovMKka31WpIgBHyNQwpMey2c9v11dvZr9VNgEF6qj8x l9gmABt6jrbTyTJxitWXihmk+83c/OOUzs3sroABjZQLdglIV20dKXNx2khAYsVby5nQ AzkQ== X-Gm-Message-State: AOAM5309aXuj9CVYH2jBgWAsS5EC88rXg9kS/q4s9gFsTOom+5xXhW4R wk8Sr2iZIpdyda9K7kwno36xU826j3J1lenYQkXNSXvqsZZ9FsbN0mH4W1otrk0I+YuKOJhWE9V CP8Dt9OiRnq8cXc0dP20y0Kk= X-Received: by 2002:a7b:ce82:0:b0:394:2514:6f07 with SMTP id q2-20020a7bce82000000b0039425146f07mr4288630wmj.56.1651750298622; Thu, 05 May 2022 04:31:38 -0700 (PDT) X-Google-Smtp-Source: ABdhPJwTaX+emZRGME2XrbVDdeWq3PLdol9IHOXQKtajyniJm9UY0h9+OnzRg+JdW6I4XRxCo9UumA== X-Received: by 2002:a7b:ce82:0:b0:394:2514:6f07 with SMTP id q2-20020a7bce82000000b0039425146f07mr4288610wmj.56.1651750298397; Thu, 05 May 2022 04:31:38 -0700 (PDT) Received: from minerva.. ([90.167.94.135]) by smtp.gmail.com with ESMTPSA id k1-20020a5d5181000000b0020c5253d8f5sm995809wrv.65.2022.05.05.04.31.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 05 May 2022 04:31:38 -0700 (PDT) From: Javier Martinez Canillas To: linux-kernel@vger.kernel.org Cc: Daniel Vetter , Daniel Vetter , Javier Martinez Canillas , Thomas Zimmermann , Daniel Vetter , Helge Deller , dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org Subject: [PATCH v2 1/4] fbdev: Prevent possible use-after-free in fb_release() Date: Thu, 5 May 2022 13:31:24 +0200 Message-Id: <20220505113128.264963-2-javierm@redhat.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220505113128.264963-1-javierm@redhat.com> References: <20220505113128.264963-1-javierm@redhat.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fbdev@vger.kernel.org From: Daniel Vetter Most fbdev drivers have issues with the fb_info lifetime, because call to framebuffer_release() from their driver's .remove callback, rather than doing from fbops.fb_destroy callback. Doing that will destroy the fb_info too early, while references to it may still exist, leading to a use-after-free error. To prevent this, check the fb_info reference counter when attempting to kfree the data structure in framebuffer_release(). That will leak it but at least will prevent the mentioned error. Signed-off-by: Daniel Vetter Signed-off-by: Javier Martinez Canillas Reviewed-by: Thomas Zimmermann --- (no changes since v1) drivers/video/fbdev/core/fbsysfs.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/video/fbdev/core/fbsysfs.c b/drivers/video/fbdev/core/fbsysfs.c index 8c1ee9ecec3d..c2a60b187467 100644 --- a/drivers/video/fbdev/core/fbsysfs.c +++ b/drivers/video/fbdev/core/fbsysfs.c @@ -80,6 +80,10 @@ void framebuffer_release(struct fb_info *info) { if (!info) return; + + if (WARN_ON(refcount_read(&info->count))) + return; + kfree(info->apertures); kfree(info); }