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=-2.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 008F1C433F5 for ; Sun, 26 Aug 2018 06:45:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C07EA216FA for ; Sun, 26 Aug 2018 06:45:35 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C07EA216FA Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726994AbeHZK1I (ORCPT ); Sun, 26 Aug 2018 06:27:08 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:53468 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726224AbeHZK1H (ORCPT ); Sun, 26 Aug 2018 06:27:07 -0400 Received: from localhost (5355525A.cm-6-6b.dynamic.ziggo.nl [83.85.82.90]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id 26DE49D2; Sun, 26 Aug 2018 06:45:31 +0000 (UTC) From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, zhang jun , Takashi Iwai Subject: [PATCH 3.18 10/56] ALSA: memalloc: Dont exceed over the requested size Date: Sun, 26 Aug 2018 08:44:31 +0200 Message-Id: <20180826064232.768743918@linuxfoundation.org> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20180826064232.320669119@linuxfoundation.org> References: <20180826064232.320669119@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Takashi Iwai commit dfef01e150824b0e6da750cacda8958188d29aea upstream. snd_dma_alloc_pages_fallback() tries to allocate pages again when the allocation fails with reduced size. But the first try actually *increases* the size to power-of-two, which may give back a larger chunk than the requested size. This confuses the callers, e.g. sgbuf assumes that the size is equal or less, and it may result in a bad loop due to the underflow and eventually lead to Oops. The code of this function seems incorrectly assuming the usage of get_order(). We need to decrease at first, then align to power-of-two. Reported-and-tested-by: he, bo Reported-by: zhang jun Cc: Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman --- sound/core/memalloc.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) --- a/sound/core/memalloc.c +++ b/sound/core/memalloc.c @@ -239,16 +239,12 @@ int snd_dma_alloc_pages_fallback(int typ int err; while ((err = snd_dma_alloc_pages(type, device, size, dmab)) < 0) { - size_t aligned_size; if (err != -ENOMEM) return err; if (size <= PAGE_SIZE) return -ENOMEM; - aligned_size = PAGE_SIZE << get_order(size); - if (size != aligned_size) - size = aligned_size; - else - size >>= 1; + size >>= 1; + size = PAGE_SIZE << get_order(size); } if (! dmab->area) return -ENOMEM;