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=-10.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,URIBL_BLOCKED, USER_AGENT_SANE_2 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 CAF95C433E0 for ; Sat, 9 Jan 2021 00:22:36 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 87F0D23A69 for ; Sat, 9 Jan 2021 00:22:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 87F0D23A69 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=mediatek.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-mediatek-bounces+linux-mediatek=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To:Date:To:From: Subject:Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=/s+sjDphxZ7IcQhUuJVnWcULjtauGJjBWC4dG1nisPo=; b=JlbnIRm2Ob635wT8tML/NDHgY iyaVcR4umS1sZGUZxmNNIZwHGnkQoe70ctFu6MmOUKT1qz6Rrdd4jbU6At53bI9UoviSdEd6mef7O 0tFm5duo7bGSSZNigPgT/VRD1ULW13cLGguvmOvQyoJvGCogRxA1tBEYtU2d6o+ImAGI+fZPZUtjt lytHw0sKLcFBrGa9ZNqTxfwK8/Ovjqat916SiQ7jitHsa1i843/FXsujw2mzqfYgcLtJLel2zNUzO 6LgGSkLNkzYVDtd1lsjGj4ow9rxIRqn7gizUF4WoY4C7hX/47XXPROKomrEVZ/UE346dSOouHneoi 2bpwKjHlw==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1ky21Q-0004pF-B4; Sat, 09 Jan 2021 00:22:24 +0000 Received: from mailgw02.mediatek.com ([216.200.240.185]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1ky21N-0004oU-9S for linux-mediatek@lists.infradead.org; Sat, 09 Jan 2021 00:22:22 +0000 X-UUID: d92e53e7898945d6b6b3db7b9cbbedff-20210108 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=mediatek.com; s=dk; h=Content-Transfer-Encoding:MIME-Version:Content-Type:References:In-Reply-To:Date:CC:To:From:Subject:Message-ID; bh=7CYUlKecezZ1BJCyWACsMHG9HSdAtzLwoRJDZJLvlmg=; b=u1nu8GhD3Ns6FKKIPusbT9IGyEvJIMTVgyiiqwP5mQaWrOqzbcKO1uymHfKBhIXPmakY4G0XIrYXFkBsVN88MP+StPa9yWXdFuwIT/gCVOspPpEC514XbTYTwX18bcf9/9otufKmOKZSLeNXg72P3rEeQos+8jlctugh+rr9Fqk=; X-UUID: d92e53e7898945d6b6b3db7b9cbbedff-20210108 Received: from mtkcas67.mediatek.inc [(172.29.193.45)] by mailgw02.mediatek.com (envelope-from ) (musrelay.mediatek.com ESMTP with TLSv1.2 ECDHE-RSA-AES256-SHA384 256/256) with ESMTP id 535487638; Fri, 08 Jan 2021 16:22:16 -0800 Received: from MTKMBS06N1.mediatek.inc (172.21.101.129) by MTKMBS62DR.mediatek.inc (172.29.94.18) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Fri, 8 Jan 2021 16:22:15 -0800 Received: from mtkcas11.mediatek.inc (172.21.101.40) by mtkmbs06n1.mediatek.inc (172.21.101.129) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Sat, 9 Jan 2021 08:22:13 +0800 Received: from [172.21.77.33] (172.21.77.33) by mtkcas11.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Sat, 9 Jan 2021 08:22:13 +0800 Message-ID: <1610151733.9343.3.camel@mtkswgap22> Subject: Re: [PATCH] mac80211: fix incorrect strlen of .write in debugfs From: Ryder Lee To: Johannes Berg Date: Sat, 9 Jan 2021 08:22:13 +0800 In-Reply-To: <0efec65815ff9e26b3da69cb35d503a90086760c.camel@sipsolutions.net> References: <20210108105643.10834-1-shayne.chen@mediatek.com> <0efec65815ff9e26b3da69cb35d503a90086760c.camel@sipsolutions.net> X-Mailer: Evolution 3.2.3-0ubuntu6 MIME-Version: 1.0 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210108_192221_521388_7C04AA24 X-CRM114-Status: GOOD ( 15.89 ) X-BeenThere: linux-mediatek@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Toke =?ISO-8859-1?Q?H=F8iland-J=F8rgensen?= , linux-wireless , linux-mediatek , Sujuan Chen , Lorenzo Bianconi , Felix Fietkau , Shayne Chen Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "Linux-mediatek" Errors-To: linux-mediatek-bounces+linux-mediatek=archiver.kernel.org@lists.infradead.org On Fri, 2021-01-08 at 21:02 +0100, Johannes Berg wrote: > This looks wrong to me, am I missing something? > > > diff --git a/net/mac80211/debugfs.c b/net/mac80211/debugfs.c > > index 9135b6f..9991a6a 100644 > > --- a/net/mac80211/debugfs.c > > +++ b/net/mac80211/debugfs.c > > @@ -120,7 +120,6 @@ static ssize_t aqm_write(struct file *file, > > { > > struct ieee80211_local *local = file->private_data; > > char buf[100]; > > - size_t len; > > > > if (count > sizeof(buf)) > > return -EINVAL; > > This ensures that count <= sizeof(buf) > > > @@ -128,10 +127,10 @@ static ssize_t aqm_write(struct file *file, > > if (copy_from_user(buf, user_buf, count)) > > return -EFAULT; > > We copy, that's fine. > > > - buf[sizeof(buf) - 1] = '\0'; > > - len = strlen(buf); > > - if (len > 0 && buf[len-1] == '\n') > > - buf[len-1] = 0; > > + if (count && buf[count - 1] == '\n') > > + buf[count - 1] = '\0'; > > This I think really was meant as strlen, because if you write something > like > > 10\n\0\0\0\0 > > before it would have parsed it as 10 still, now it gets confused? > > I guess I'm not worried about that though. I think the problem only happens on airtime_flags_write() that uses kstrtou16() > > + buf[count] = '\0'; > > But if count == sizeof(buf) then this is an out-of-bounds write. Right. Then, we can if (count >= sizeof(buf)) return -EINVAL; Ryder _______________________________________________ Linux-mediatek mailing list Linux-mediatek@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-mediatek