From patchwork Sun Dec 8 21:22:06 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Remi Pommarel X-Patchwork-Id: 11278283 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 85612138D for ; Sun, 8 Dec 2019 21:13:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 64F1320637 for ; Sun, 8 Dec 2019 21:13:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726586AbfLHVNq (ORCPT ); Sun, 8 Dec 2019 16:13:46 -0500 Received: from relay12.mail.gandi.net ([217.70.178.232]:55857 "EHLO relay12.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725554AbfLHVNp (ORCPT ); Sun, 8 Dec 2019 16:13:45 -0500 Received: from localhost (unknown [88.190.179.123]) (Authenticated sender: repk@triplefau.lt) by relay12.mail.gandi.net (Postfix) with ESMTPSA id 4C24A200006; Sun, 8 Dec 2019 21:13:41 +0000 (UTC) From: Remi Pommarel To: Neil Armstrong , Jerome Brunet Cc: Michael Turquette , Stephen Boyd , Kevin Hilman , linux-amlogic@lists.infradead.org, linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Remi Pommarel Subject: [PATCH] clk: meson: pll: Fix by 0 division in __pll_params_to_rate() Date: Sun, 8 Dec 2019 22:22:06 +0100 Message-Id: <20191208212206.16808-1-repk@triplefau.lt> X-Mailer: git-send-email 2.24.0 MIME-Version: 1.0 Sender: linux-clk-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-clk@vger.kernel.org Some meson pll registers can be initialized with 0 as N value, introducing the following division by 0 when computing rate : UBSAN: Undefined behaviour in drivers/clk/meson/clk-pll.c:75:9 division by zero CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.4.0-rc3-608075-g86c9af8630e1-dirty #400 Call trace: dump_backtrace+0x0/0x1c0 show_stack+0x14/0x20 dump_stack+0xc4/0x100 ubsan_epilogue+0x14/0x68 __ubsan_handle_divrem_overflow+0x98/0xb8 __pll_params_to_rate+0xdc/0x140 meson_clk_pll_recalc_rate+0x278/0x3a0 __clk_register+0x7c8/0xbb0 devm_clk_hw_register+0x54/0xc0 meson_eeclkc_probe+0xf4/0x1a0 platform_drv_probe+0x54/0xd8 really_probe+0x16c/0x438 driver_probe_device+0xb0/0xf0 device_driver_attach+0x94/0xa0 __driver_attach+0x70/0x108 bus_for_each_dev+0xd8/0x128 driver_attach+0x30/0x40 bus_add_driver+0x1b0/0x2d8 driver_register+0xbc/0x1d0 __platform_driver_register+0x78/0x88 axg_driver_init+0x18/0x20 do_one_initcall+0xc8/0x24c kernel_init_freeable+0x2b0/0x344 kernel_init+0x10/0x128 ret_from_fork+0x10/0x18 This checks if N is null before doing the division. Fixes: 8289aafa4f36 ("clk: meson: improve pll driver results with frac") Signed-off-by: Remi Pommarel --- drivers/clk/meson/clk-pll.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/clk/meson/clk-pll.c b/drivers/clk/meson/clk-pll.c index ddb1e5634739..6649659f216a 100644 --- a/drivers/clk/meson/clk-pll.c +++ b/drivers/clk/meson/clk-pll.c @@ -66,6 +66,10 @@ static unsigned long __pll_params_to_rate(unsigned long parent_rate, (1 << pll->frac.width)); } + /* Avoid by zero division */ + if (n == 0) + return 0; + return DIV_ROUND_UP_ULL(rate, n); }