From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751380AbdFBVcF (ORCPT ); Fri, 2 Jun 2017 17:32:05 -0400 Received: from mail-it0-f65.google.com ([209.85.214.65]:36183 "EHLO mail-it0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750966AbdFBVcE (ORCPT ); Fri, 2 Jun 2017 17:32:04 -0400 Message-ID: <1496439121.13303.1.camel@gmail.com> Subject: Re: [PATCH v4] add the option of fortified string.h functions From: Daniel Micay To: Andrew Morton Cc: linux-mm@kvack.org, Kees Cook , kernel-hardening@lists.openwall.com, linux-kernel , Mark Rutland , Daniel Axtens , Moni Shoua , Doug Ledford , Sean Hefty , Hal Rosenstock , linux-rdma@vger.kernel.org Date: Fri, 02 Jun 2017 17:32:01 -0400 In-Reply-To: <20170602140743.274b9babba6118bfd12c7a26@linux-foundation.org> References: <20170526095404.20439-1-danielmicay@gmail.com> <20170602140743.274b9babba6118bfd12c7a26@linux-foundation.org> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.24.2 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2017-06-02 at 14:07 -0700, Andrew Morton wrote: > On Fri, 26 May 2017 05:54:04 -0400 Daniel Micay > wrote: > > > This adds support for compiling with a rough equivalent to the glibc > > _FORTIFY_SOURCE=1 feature, providing compile-time and runtime buffer > > overflow checks for string.h functions when the compiler determines > > the > > size of the source or destination buffer at compile-time. Unlike > > glibc, > > it covers buffer reads in addition to writes. > > Did we find a bug in drivers/infiniband/sw/rxe/rxe_resp.c? > > i386 allmodconfig: > > In file included from ./include/linux/bitmap.h:8:0, > from ./include/linux/cpumask.h:11, > from ./include/linux/mm_types_task.h:13, > from ./include/linux/mm_types.h:4, > from ./include/linux/kmemcheck.h:4, > from ./include/linux/skbuff.h:18, > from drivers/infiniband/sw/rxe/rxe_resp.c:34: > In function 'memcpy', > inlined from 'send_atomic_ack.constprop' at > drivers/infiniband/sw/rxe/rxe_resp.c:998:2, > inlined from 'acknowledge' at > drivers/infiniband/sw/rxe/rxe_resp.c:1026:3, > inlined from 'rxe_responder' at > drivers/infiniband/sw/rxe/rxe_resp.c:1286:10: > ./include/linux/string.h:309:4: error: call to '__read_overflow2' > declared with attribute error: detected read beyond size of object > passed as 2nd parameter > __read_overflow2(); > > > If so, can you please interpret this for the infiniband developers? It copies sizeof(skb->cb) bytes with memcpy which is 48 bytes since cb is a 48 byte char array in `struct sk_buff`. The source buffer is a `struct rxe_pkt_info`: struct rxe_pkt_info { struct rxe_dev *rxe; /* device that owns packet */ struct rxe_qp *qp; /* qp that owns packet */ struct rxe_send_wqe *wqe; /* send wqe */ u8 *hdr; /* points to bth */ u32 mask; /* useful info about pkt */ u32 psn; /* bth psn of packet */ u16 pkey_index; /* partition of pkt */ u16 paylen; /* length of bth - icrc */ u8 port_num; /* port pkt received on */ u8 opcode; /* bth opcode of packet */ u8 offset; /* bth offset from pkt->hdr */ }; That looks like 32 bytes (1 byte of padding) on 32-bit and 48 bytes on 64-bit (1 byte of padding), so on 32-bit there's a read overflow of 16 bytes from the stack here.