From patchwork Fri Mar 12 21:21:19 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Uwe_Kleine-K=C3=B6nig?= X-Patchwork-Id: 1452397 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=linux-pwm-owner@vger.kernel.org; receiver=) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4DxzKd4hXLz9sS8 for ; Sat, 13 Mar 2021 08:22:13 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234964AbhCLVVd (ORCPT ); Fri, 12 Mar 2021 16:21:33 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35482 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235116AbhCLVVY (ORCPT ); Fri, 12 Mar 2021 16:21:24 -0500 Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 32D51C061574 for ; Fri, 12 Mar 2021 13:21:24 -0800 (PST) Received: from ptx.hi.pengutronix.de ([2001:67c:670:100:1d::c0]) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1lKpDm-0002g4-5z; Fri, 12 Mar 2021 22:21:22 +0100 Received: from ukl by ptx.hi.pengutronix.de with local (Exim 4.92) (envelope-from ) id 1lKpDl-0003S5-J0; Fri, 12 Mar 2021 22:21:21 +0100 From: =?utf-8?q?Uwe_Kleine-K=C3=B6nig?= To: Thierry Reding , Lee Jones Cc: linux-pwm@vger.kernel.org, kernel@pengutronix.de, Guru Das Srinagesh Subject: [PATCH v2] pwm: Soften potential loss of precision in compat code Date: Fri, 12 Mar 2021 22:21:19 +0100 Message-Id: <20210312212119.1342666-1-u.kleine-koenig@pengutronix.de> X-Mailer: git-send-email 2.30.1 MIME-Version: 1.0 X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::c0 X-SA-Exim-Mail-From: ukl@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-pwm@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pwm@vger.kernel.org The legacy callback .config() only uses int for period and duty_cycle while the corresponding values in struct pwm_state are u64. To prevent that a value bigger than INT_MAX is discarded to a very small value, explicitly check for big values and pass INT_MAX instead of discarding. Signed-off-by: Uwe Kleine-König Acked-by: Guru Das Srinagesh --- Hello, compared to (implicit) v1 I added a comment and used min instead of open coding the calculation. Best regards Uwe drivers/pwm/core.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c index 4b3779d58c5a..7d0266bc5fcb 100644 --- a/drivers/pwm/core.c +++ b/drivers/pwm/core.c @@ -605,9 +605,18 @@ int pwm_apply_state(struct pwm_device *pwm, const struct pwm_state *state) if (state->period != pwm->state.period || state->duty_cycle != pwm->state.duty_cycle) { + int duty_cycle, period; + + /* + * The legacy callbacks use only (signed!) int for + * period and duty_cycle compared to u64 in struct + * pwm_state. So clamp the values to INT_MAX. + */ + period = min(state->period, (u64)INT_MAX); + duty_cycle = min(state->duty_cycle, (u64)INT_MAX); + err = chip->ops->config(pwm->chip, pwm, - state->duty_cycle, - state->period); + duty_cycle, period); if (err) return err;