From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it0-f72.google.com (mail-it0-f72.google.com [209.85.214.72]) by kanga.kvack.org (Postfix) with ESMTP id 7CE966B0292 for ; Sat, 3 Jun 2017 01:07:14 -0400 (EDT) Received: by mail-it0-f72.google.com with SMTP id 67so93289371itx.11 for ; Fri, 02 Jun 2017 22:07:14 -0700 (PDT) Received: from mail-it0-x229.google.com (mail-it0-x229.google.com. [2607:f8b0:4001:c0b::229]) by mx.google.com with ESMTPS id p195si4650415itb.11.2017.06.02.22.07.13 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 02 Jun 2017 22:07:13 -0700 (PDT) Received: by mail-it0-x229.google.com with SMTP id m47so24024048iti.1 for ; Fri, 02 Jun 2017 22:07:13 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <1496439121.13303.1.camel@gmail.com> References: <20170526095404.20439-1-danielmicay@gmail.com> <20170602140743.274b9babba6118bfd12c7a26@linux-foundation.org> <1496439121.13303.1.camel@gmail.com> From: Kees Cook Date: Fri, 2 Jun 2017 22:07:12 -0700 Message-ID: Subject: Re: [PATCH v4] add the option of fortified string.h functions Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton , Moni Shoua , Doug Ledford , Sean Hefty , Hal Rosenstock Cc: Daniel Micay , Linux-MM , "kernel-hardening@lists.openwall.com" , linux-kernel , Mark Rutland , Daniel Axtens , linux-rdma@vger.kernel.org On Fri, Jun 2, 2017 at 2:32 PM, Daniel Micay wrote: > 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. This should work (untested): diff --git a/drivers/infiniband/sw/rxe/rxe_resp.c b/drivers/infiniband/sw/rxe/rxe_resp.c index 23039768f541..7b226deb83bb 100644 --- a/drivers/infiniband/sw/rxe/rxe_resp.c +++ b/drivers/infiniband/sw/rxe/rxe_resp.c @@ -995,7 +995,9 @@ static int send_atomic_ack(struct rxe_qp *qp, struct rxe_pkt_info *pkt, free_rd_atomic_resource(qp, res); rxe_advance_resp_resource(qp); - memcpy(SKB_TO_PKT(skb), &ack_pkt, sizeof(skb->cb)); + memcpy(SKB_TO_PKT(skb), &ack_pkt, sizeof(ack_ptr)); + memset(SKB_TO_PKT(skb) + sizeof(ack_ptr), 0, + sizeof(skb->cb) - sizeof(ack_ptr)); res->type = RXE_ATOMIC_MASK; res->atomic.skb = skb; Andrew, there are other fortify fixes too: https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git/commit/?h=kspp/fortify&id=af6b0151896240457ef0fdc18ace533c3d3fbb75 https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git/commit/?h=kspp/fortify&id=186eaf81b43bf90d6b533732fb11ad31ca27df9d https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git/commit/?h=kspp/fortify&id=95d589f21b3aef757f0eb3d0224b78648a4b22d2 https://github.com/thestinger/linux-hardened/commit/576e64469b0c4634c007445c5f16bfde610b3600 Do you want me to resend these for you to carry, or reping maintainers? Other fixes have already landed in -next. (And there are two arm64 fixes, too.) -Kees -- Kees Cook Pixel Security -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org