From owner-freebsd-net@freebsd.org Thu Nov 22 06:50:13 2018 Return-Path: Delivered-To: freebsd-net@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 762E6113C142 for ; Thu, 22 Nov 2018 06:50:13 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from mailman.ysv.freebsd.org (mailman.ysv.freebsd.org [IPv6:2001:1900:2254:206a::50:5]) by mx1.freebsd.org (Postfix) with ESMTP id 095ED8E2F9 for ; Thu, 22 Nov 2018 06:50:13 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: by mailman.ysv.freebsd.org (Postfix) id BB909113C141; Thu, 22 Nov 2018 06:50:12 +0000 (UTC) Delivered-To: net@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 80CE4113C140 for ; Thu, 22 Nov 2018 06:50:12 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from mxrelay.ysv.freebsd.org (mxrelay.ysv.freebsd.org [IPv6:2001:1900:2254:206a::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (Client CN "mxrelay.ysv.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 1FFDA8E2F1 for ; Thu, 22 Nov 2018 06:50:12 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org (kenobi.freebsd.org [IPv6:2001:1900:2254:206a::16:76]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.ysv.freebsd.org (Postfix) with ESMTPS id 342A57B6F for ; Thu, 22 Nov 2018 06:50:11 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org ([127.0.1.118]) by kenobi.freebsd.org (8.15.2/8.15.2) with ESMTP id wAM6oBu8043134 for ; Thu, 22 Nov 2018 06:50:11 GMT (envelope-from bugzilla-noreply@freebsd.org) Received: (from www@localhost) by kenobi.freebsd.org (8.15.2/8.15.2/Submit) id wAM6oBf8043133 for net@FreeBSD.org; Thu, 22 Nov 2018 06:50:11 GMT (envelope-from bugzilla-noreply@freebsd.org) X-Authentication-Warning: kenobi.freebsd.org: www set sender to bugzilla-noreply@freebsd.org using -f From: bugzilla-noreply@freebsd.org To: net@FreeBSD.org Subject: [Bug 230498] Fatal trap 12: page fault while in kernel mode in sysctl_dumpentry from sysctl NET_RT_DUMP Date: Thu, 22 Nov 2018 06:50:11 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: kern X-Bugzilla-Version: 11.2-STABLE X-Bugzilla-Keywords: X-Bugzilla-Severity: Affects Some People X-Bugzilla-Who: ae@FreeBSD.org X-Bugzilla-Status: New X-Bugzilla-Resolution: X-Bugzilla-Priority: --- X-Bugzilla-Assigned-To: net@FreeBSD.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: https://bugs.freebsd.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-Rspamd-Queue-Id: 095ED8E2F9 X-Spamd-Result: default: False [0.71 / 15.00]; local_wl_from(0.00)[freebsd.org]; NEURAL_HAM_SHORT(-0.07)[-0.065,0]; NEURAL_SPAM_LONG(0.42)[0.416,0]; NEURAL_SPAM_MEDIUM(0.36)[0.355,0]; ASN(0.00)[asn:10310, ipnet:2001:1900:2254::/48, country:US] X-Rspamd-Server: mx1.freebsd.org X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 22 Nov 2018 06:50:13 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D230498 --- Comment #16 from Andrey V. Elsukov --- (In reply to ian from comment #13) > I did make a pretty naive fix for this shortly after reporting it as the > system in question was crashing several times a day. Since applying this I > have has no further issues with it. It does mean the application querying > gets back some null pointers, but its likely better the application exits > (if it does not check for NULL pointers) than the entire system crashing ? >=20 > Index: rtsock.c > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > --- rtsock.c (revision 339318) > +++ rtsock.c (working copy) > @@ -1556,8 +1556,10 @@ > rt_mask(rt), &ss); > info.rti_info[RTAX_GENMASK] =3D 0; > if (rt->rt_ifp) { > - info.rti_info[RTAX_IFP] =3D rt->rt_ifp->if_addr->ifa_addr; > - info.rti_info[RTAX_IFA] =3D rt->rt_ifa->ifa_addr; > + if (rt->rt_ifp->if_addr) > + info.rti_info[RTAX_IFP] =3D > rt->rt_ifp->if_addr->ifa_addr; > + if (rt->rt_ifa) > + info.rti_info[RTAX_IFA] =3D rt->rt_ifa->ifa_addr; > if (rt->rt_ifp->if_flags & IFF_POINTOPOINT) > info.rti_info[RTAX_BRD] =3D rt->rt_ifa->ifa_dstad= dr; > } rt->rt_ifa should be safe to dereference, since rtentry holds reference to = ifa and it won't be freed. But access to rt_ifp->if_addr is not easy to protect= in stable/11. The problem happens due to interface is destroying in the time, = when we are doing iteration through routes. And even if you add NULL check here, there is not any guarantee that you won't make access to already freed memo= ry in the rtsock_msg_buffer() a bit later, when you will make access to info.rti_info[]. Also I think an application may expect presence of both RTAX_IFP and RTAX_IFA pointers. --=20 You are receiving this mail because: You are the assignee for the bug.=