From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:52942 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934554AbdAFVwL (ORCPT ); Fri, 6 Jan 2017 16:52:11 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Russell Currey , Joel Stanley , Daniel Vetter Subject: [PATCH 4.8 36/96] drivers/gpu/drm/ast: Fix infinite loop if read fails Date: Fri, 6 Jan 2017 22:43:24 +0100 Message-Id: <20170106214229.196766509@linuxfoundation.org> In-Reply-To: <20170106214227.601120243@linuxfoundation.org> References: <20170106214227.601120243@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.8-stable review patch. If anyone has any objections, please let me know. ------------------ From: Russell Currey commit 298360af3dab45659810fdc51aba0c9f4097e4f6 upstream. ast_get_dram_info() configures a window in order to access BMC memory. A BMC register can be configured to disallow this, and if so, causes an infinite loop in the ast driver which renders the system unusable. Fix this by erroring out if an error is detected. On powerpc systems with EEH, this leads to the device being fenced and the system continuing to operate. Signed-off-by: Russell Currey Reviewed-by: Joel Stanley Signed-off-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/20161215051241.20815-1-ruscur@russell.cc Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/ast/ast_main.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) --- a/drivers/gpu/drm/ast/ast_main.c +++ b/drivers/gpu/drm/ast/ast_main.c @@ -223,7 +223,8 @@ static int ast_get_dram_info(struct drm_ ast_write32(ast, 0x10000, 0xfc600309); do { - ; + if (pci_channel_offline(dev->pdev)) + return -EIO; } while (ast_read32(ast, 0x10000) != 0x01); data = ast_read32(ast, 0x10004); @@ -428,7 +429,9 @@ int ast_driver_load(struct drm_device *d ast_detect_chip(dev, &need_post); if (ast->chip != AST1180) { - ast_get_dram_info(dev); + ret = ast_get_dram_info(dev); + if (ret) + goto out_free; ast->vram_size = ast_get_vram_info(dev); DRM_INFO("dram %d %d %d %08x\n", ast->mclk, ast->dram_type, ast->dram_bus_width, ast->vram_size); }