From patchwork Wed Sep 11 14:29:52 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kaixin Wang X-Patchwork-Id: 827964 Received: from smtpbgbr2.qq.com (smtpbgbr2.qq.com [54.207.22.56]) (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 BFF03185606; Wed, 11 Sep 2024 14:30:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=54.207.22.56 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726065062; cv=none; b=KeKjVNi4LDOBe9pLnzGschQG6yPej/ipb6Qcvnlmk/ttdXg1nvVvls1AE5MDPAf4p240i4GUMbfyUGDtWuerR6TOO1KIMltf9JCE4NQgF/Zv4hGtABNwzslIfLnGPJ0CarGf2pmStb8dqSpKUDjaI1l5hC0knn+bf6T6LIgXTqo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726065062; c=relaxed/simple; bh=+0RRQI371JwlBeboT9GF49cq6sF+GAbP9dyGVitN45E=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=IaRxBqgPI64bEii9hDJhxysgLgHshZ4wBQhaHha00MZpNZDW4tLwL4mU862hV1JV7Yb6eGJTUTv4sHD/4oXrxv7+cawUReUDDW9mh8O7+U/QtqN4Hhw9rx+zhHySo8oKoD/SQzULzUzUXf4dcA5jO+FYKMCIc7lParG4LFAKkt4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=m.fudan.edu.cn; spf=pass smtp.mailfrom=m.fudan.edu.cn; arc=none smtp.client-ip=54.207.22.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=m.fudan.edu.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=m.fudan.edu.cn X-QQ-mid: bizesmtpsz2t1726064993t5ok0ar X-QQ-Originating-IP: P6ukSmdqm9PfLsf7wEuHBvtMtOeR6xq2pUfo5KSx/GY= Received: from fastnlp.. ( [202.120.234.41]) by bizesmtp.qq.com (ESMTP) with id ; Wed, 11 Sep 2024 22:29:43 +0800 (CST) X-QQ-SSF: 0000000000000000000000000000000 X-QQ-GoodBg: 0 X-BIZMAIL-ID: 3987430628644740193 From: Kaixin Wang To: deller@gmx.de Cc: 21210240012@m.fudan.edu.cn, 21302010073@m.fudan.edu.cn, linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, kuninori.morimoto.gx@renesas.com, laurent.pinchart@ideasonboard.com, Kaixin Wang Subject: [PATCH] fbdev: pxafb: Fix use after free vulnerability in pxafb_driver Driver Due to Race Condition Date: Wed, 11 Sep 2024 22:29:52 +0800 Message-Id: <20240911142952.833223-1-kxwang23@m.fudan.edu.cn> X-Mailer: git-send-email 2.25.1 Precedence: bulk X-Mailing-List: linux-fbdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-QQ-SENDSIZE: 520 Feedback-ID: bizesmtpsz:m.fudan.edu.cn:qybglogicsvrsz:qybglogicsvrsz4a-0 In the pxafb_probe function, it calls the pxafb_init_fbinfo function, after which &fbi->task is associated with pxafb_task. Moreover, within this pxafb_init_fbinfo function, the pxafb_blank function within the &pxafb_ops struct is capable of scheduling work. If we remove the module which will call pxafb_remove to make cleanup, it will call unregister_framebuffer function which can call do_unregister_framebuffer to free fbi->fb through put_fb_info(fb_info), while the work mentioned above will be used. The sequence of operations that may lead to a UAF bug is as follows: CPU0 CPU1 | pxafb_task pxafb_remove | unregister_framebuffer(info) | do_unregister_framebuffer(fb_info) | put_fb_info(fb_info) | // free fbi->fb | set_ctrlr_state(fbi, state) | __pxafb_lcd_power(fbi, 0) | fbi->lcd_power(on, &fbi->fb.var) | //use fbi->fb Fix it by ensuring that the work is canceled before proceeding with the cleanup in pxafb_remove. Note that only root user can remove the driver at runtime. Signed-off-by: Kaixin Wang --- drivers/video/fbdev/pxafb.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/video/fbdev/pxafb.c b/drivers/video/fbdev/pxafb.c index 2ef56fa28aff..5ce02495cda6 100644 --- a/drivers/video/fbdev/pxafb.c +++ b/drivers/video/fbdev/pxafb.c @@ -2403,6 +2403,7 @@ static void pxafb_remove(struct platform_device *dev) info = &fbi->fb; pxafb_overlay_exit(fbi); + cancel_work_sync(&fbi->task); unregister_framebuffer(info); pxafb_disable_controller(fbi);