From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from eu-smtp-delivery-151.mimecast.com ([146.101.78.151]:23571 "EHLO eu-smtp-delivery-151.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726319AbeJORK3 (ORCPT ); Mon, 15 Oct 2018 13:10:29 -0400 From: David Laight To: "'ndesaulniers@google.com'" , "jejb@linux.vnet.ibm.com" , "dhowells@redhat.com" CC: "natechancellor@gmail.com" , "ebiggers@google.com" , Mimi Zohar , James Morris , "Serge E. Hallyn" , "linux-integrity@vger.kernel.org" , "keyrings@vger.kernel.org" , "linux-security-module@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: RE: [PATCH] KEYS: trusted: fix -Wvarags warning Date: Mon, 15 Oct 2018 09:26:02 +0000 Message-ID: <0180360cfcb5458d8ff099744e8884d4@AcuMS.aculab.com> References: <1539274203.2623.56.camel@linux.vnet.ibm.com> <20181011203126.15338-1-ndesaulniers@google.com> In-Reply-To: <20181011203126.15338-1-ndesaulniers@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-integrity-owner@vger.kernel.org List-ID: From: ndesaulniers@google.com > Sent: 11 October 2018 21:31 ... > by swapping h2 and h3. > > security/keys/trusted.c:146:17: warning: passing an object that > undergoes default > argument promotion to 'va_start' has undefined behavior [-Wvarargs] > va_start(argp, h3); > ^ > security/keys/trusted.c:126:37: note: parameter of type 'unsigned > char' is declared here > unsigned char *h2, unsigned char h3, ...) > ^ > Specifically, it seems that both the C90 (4.8.1.1) and C11 (7.16.1.4) > standards explicitly call this out as undefined behavior: I guess that problems arise when all the arguments are stacked and va_start/va_arg use naive pointer manipulation. In that case &h3 might be 4n+3 aligned so va_arg() will access misaligned stack locations. I doubt any modern compilers (where va_start and va_arg are builtins) will get this 'wrong' even when all arguments are stacked. Seems clang is being over cautious. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales) 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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=unavailable 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 102B0C7112A for ; Mon, 15 Oct 2018 09:26:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ED5CA2054F for ; Mon, 15 Oct 2018 09:26:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org ED5CA2054F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ACULAB.COM Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-integrity-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726614AbeJORK3 (ORCPT ); Mon, 15 Oct 2018 13:10:29 -0400 Received: from eu-smtp-delivery-151.mimecast.com ([146.101.78.151]:23571 "EHLO eu-smtp-delivery-151.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726319AbeJORK3 (ORCPT ); Mon, 15 Oct 2018 13:10:29 -0400 Received: from AcuMS.aculab.com (156.67.243.126 [156.67.243.126]) (Using TLS) by eu-smtp-1.mimecast.com with ESMTP id uk-mta-145-TY_yltWpMzSa0j3fDrgy7w-1; Mon, 15 Oct 2018 10:26:00 +0100 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) by AcuMS.aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) with Microsoft SMTP Server (TLS) id 15.0.1347.2; Mon, 15 Oct 2018 10:26:02 +0100 Received: from AcuMS.Aculab.com ([fe80::43c:695e:880f:8750]) by AcuMS.aculab.com ([fe80::43c:695e:880f:8750%12]) with mapi id 15.00.1347.000; Mon, 15 Oct 2018 10:26:02 +0100 From: David Laight To: "'ndesaulniers@google.com'" , "jejb@linux.vnet.ibm.com" , "dhowells@redhat.com" CC: "natechancellor@gmail.com" , "ebiggers@google.com" , Mimi Zohar , James Morris , "Serge E. Hallyn" , "linux-integrity@vger.kernel.org" , "keyrings@vger.kernel.org" , "linux-security-module@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: RE: [PATCH] KEYS: trusted: fix -Wvarags warning Thread-Topic: [PATCH] KEYS: trusted: fix -Wvarags warning Thread-Index: AQHUYaFtz6yVKVwaakuhVxq6kXztuKUgDL3Q Date: Mon, 15 Oct 2018 09:26:02 +0000 Message-ID: <0180360cfcb5458d8ff099744e8884d4@AcuMS.aculab.com> References: <1539274203.2623.56.camel@linux.vnet.ibm.com> <20181011203126.15338-1-ndesaulniers@google.com> In-Reply-To: <20181011203126.15338-1-ndesaulniers@google.com> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-MC-Unique: TY_yltWpMzSa0j3fDrgy7w-1 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: base64 Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org Message-ID: <20181015092602.lI4hBvr-AVjCfM6TjoszcxHkJ3xKRBFKV0YjswEZv08@z> RnJvbTogbmRlc2F1bG5pZXJzQGdvb2dsZS5jb20NCj4gU2VudDogMTEgT2N0b2JlciAyMDE4IDIx OjMxDQouLi4NCj4gYnkgc3dhcHBpbmcgaDIgYW5kIGgzLg0KPiANCj4gc2VjdXJpdHkva2V5cy90 cnVzdGVkLmM6MTQ2OjE3OiB3YXJuaW5nOiBwYXNzaW5nIGFuIG9iamVjdCB0aGF0DQo+IHVuZGVy Z29lcyBkZWZhdWx0DQo+ICAgICAgIGFyZ3VtZW50IHByb21vdGlvbiB0byAndmFfc3RhcnQnIGhh cyB1bmRlZmluZWQgYmVoYXZpb3IgWy1XdmFyYXJnc10NCj4gICAgICAgICB2YV9zdGFydChhcmdw LCBoMyk7DQo+ICAgICAgICAgICAgICAgICAgICAgICAgXg0KPiBzZWN1cml0eS9rZXlzL3RydXN0 ZWQuYzoxMjY6Mzc6IG5vdGU6IHBhcmFtZXRlciBvZiB0eXBlICd1bnNpZ25lZA0KPiBjaGFyJyBp cyBkZWNsYXJlZCBoZXJlDQo+IHVuc2lnbmVkIGNoYXIgKmgyLCB1bnNpZ25lZCBjaGFyIGgzLCAu Li4pDQo+ICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICBeDQo+IFNwZWNpZmljYWxseSwg aXQgc2VlbXMgdGhhdCBib3RoIHRoZSBDOTAgKDQuOC4xLjEpIGFuZCBDMTEgKDcuMTYuMS40KQ0K PiBzdGFuZGFyZHMgZXhwbGljaXRseSBjYWxsIHRoaXMgb3V0IGFzIHVuZGVmaW5lZCBiZWhhdmlv cjoNCg0KSSBndWVzcyB0aGF0IHByb2JsZW1zIGFyaXNlIHdoZW4gYWxsIHRoZSBhcmd1bWVudHMg YXJlIHN0YWNrZWQNCmFuZCB2YV9zdGFydC92YV9hcmcgdXNlIG5haXZlIHBvaW50ZXIgbWFuaXB1 bGF0aW9uLg0KSW4gdGhhdCBjYXNlICZoMyBtaWdodCBiZSA0biszIGFsaWduZWQgc28gdmFfYXJn KCkgd2lsbCBhY2Nlc3MNCm1pc2FsaWduZWQgc3RhY2sgbG9jYXRpb25zLg0KDQpJIGRvdWJ0IGFu eSBtb2Rlcm4gY29tcGlsZXJzICh3aGVyZSB2YV9zdGFydCBhbmQgdmFfYXJnIGFyZSBidWlsdGlu cykNCndpbGwgZ2V0IHRoaXMgJ3dyb25nJyBldmVuIHdoZW4gYWxsIGFyZ3VtZW50cyBhcmUgc3Rh Y2tlZC4NCg0KU2VlbXMgY2xhbmcgaXMgYmVpbmcgb3ZlciBjYXV0aW91cy4NCg0KCURhdmlkDQoN Ci0NClJlZ2lzdGVyZWQgQWRkcmVzcyBMYWtlc2lkZSwgQnJhbWxleSBSb2FkLCBNb3VudCBGYXJt LCBNaWx0b24gS2V5bmVzLCBNSzEgMVBULCBVSw0KUmVnaXN0cmF0aW9uIE5vOiAxMzk3Mzg2IChX YWxlcykNCg==