From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DAB09C169C4 for ; Sun, 3 Feb 2019 13:57:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A06812084A for ; Sun, 3 Feb 2019 13:57:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729312AbfBCN5a (ORCPT ); Sun, 3 Feb 2019 08:57:30 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:53920 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728392AbfBCNuD (ORCPT ); Sun, 3 Feb 2019 08:50:03 -0500 Received: from cable-78.29.236.164.coditel.net ([78.29.236.164] helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1gqI9p-0003tp-Ba; Sun, 03 Feb 2019 13:50:01 +0000 Received: from ben by deadeye with local (Exim 4.92-RC4) (envelope-from ) id 1gqI9l-0007HW-Fg; Sun, 03 Feb 2019 14:49:57 +0100 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, Denis Kirjanov , "Takashi Iwai" Date: Sun, 03 Feb 2019 14:45:08 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 226/305] ALSA: ac97: Fix incorrect bit shift at AC97-SPSA control write In-Reply-To: X-SA-Exim-Connect-IP: 78.29.236.164 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.63-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Takashi Iwai commit 7194eda1ba0872d917faf3b322540b4f57f11ba5 upstream. The function snd_ac97_put_spsa() gets the bit shift value from the associated private_value, but it extracts too much; the current code extracts 8 bit values in bits 8-15, but this is a combination of two nibbles (bits 8-11 and bits 12-15) for left and right shifts. Due to the incorrect bits extraction, the actual shift may go beyond the 32bit value, as spotted recently by UBSAN check: UBSAN: Undefined behaviour in sound/pci/ac97/ac97_codec.c:836:7 shift exponent 68 is too large for 32-bit type 'int' This patch fixes the shift value extraction by masking the properly with 0x0f instead of 0xff. Reported-and-tested-by: Meelis Roos Signed-off-by: Takashi Iwai Signed-off-by: Ben Hutchings --- sound/pci/ac97/ac97_codec.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/sound/pci/ac97/ac97_codec.c +++ b/sound/pci/ac97/ac97_codec.c @@ -829,7 +829,7 @@ static int snd_ac97_put_spsa(struct snd_ { struct snd_ac97 *ac97 = snd_kcontrol_chip(kcontrol); int reg = kcontrol->private_value & 0xff; - int shift = (kcontrol->private_value >> 8) & 0xff; + int shift = (kcontrol->private_value >> 8) & 0x0f; int mask = (kcontrol->private_value >> 16) & 0xff; // int invert = (kcontrol->private_value >> 24) & 0xff; unsigned short value, old, new;