From owner-freebsd-bugs@freebsd.org Tue Jan 26 17:29:06 2016 Return-Path: Delivered-To: freebsd-bugs@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 4A67EA46F06 for ; Tue, 26 Jan 2016 17:29:06 +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 mx1.freebsd.org (Postfix) with ESMTPS id 315AB1C9E for ; Tue, 26 Jan 2016 17:29:06 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from bugs.freebsd.org ([127.0.1.118]) by kenobi.freebsd.org (8.15.2/8.15.2) with ESMTP id u0QHT6Bv071834 for ; Tue, 26 Jan 2016 17:29:06 GMT (envelope-from bugzilla-noreply@freebsd.org) From: bugzilla-noreply@freebsd.org To: freebsd-bugs@FreeBSD.org Subject: [Bug 206648] Fix double strlen in ktrstruct Date: Tue, 26 Jan 2016 17:29:06 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: new X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: kern X-Bugzilla-Version: 11.0-CURRENT X-Bugzilla-Keywords: X-Bugzilla-Severity: Affects Many People X-Bugzilla-Who: ecturt@gmail.com X-Bugzilla-Status: New X-Bugzilla-Resolution: X-Bugzilla-Priority: --- X-Bugzilla-Assigned-To: freebsd-bugs@FreeBSD.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: bug_id short_desc product version rep_platform op_sys bug_status bug_severity priority component assigned_to reporter Message-ID: 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-BeenThere: freebsd-bugs@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: Bug reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 26 Jan 2016 17:29:06 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D206648 Bug ID: 206648 Summary: Fix double strlen in ktrstruct Product: Base System Version: 11.0-CURRENT Hardware: Any OS: Any Status: New Severity: Affects Many People Priority: --- Component: kern Assignee: freebsd-bugs@FreeBSD.org Reporter: ecturt@gmail.com The `ktrstruct` function from `sys/kern/kern_ktrace.c` was calling `strlen`= on `name` twice, which could have lead to a race attack (contents of `name` changed between these two calls). I've verified that this wasn't previously optimised into a single call to `strlen` in a compiled kernel. There is no way to exploit this bug since it is only used by macros which p= ass strings with static contents: #define ktrsockaddr(s) \ ktrstruct("sockaddr", (s), ((struct sockaddr *)(s))->sa_len) #define ktrstat(s) \ ktrstruct("stat", (s), sizeof(struct stat)) However, this situation is fragile, and should be patched to prevent the possibility of being exploited in the future if ever `ktrstruct` is passed a non-static name. At the very least, this patch will also be a very minor optimisation. Current: void ktrstruct(name, data, datalen) const char *name; void *data; size_t datalen; { struct ktr_request *req; char *buf =3D NULL; size_t buflen; if (!data) datalen =3D 0; buflen =3D strlen(name) + 1 + datalen; buf =3D malloc(buflen, M_KTRACE, M_WAITOK); strcpy(buf, name); bcopy(data, buf + strlen(name) + 1, datalen); if ((req =3D ktr_getrequest(KTR_STRUCT)) =3D=3D NULL) { free(buf, M_KTRACE); return; } req->ktr_buffer =3D buf; req->ktr_header.ktr_len =3D buflen; ktr_submitrequest(curthread, req); } Patched: void ktrstruct(name, data, datalen) const char *name; void *data; size_t datalen; { struct ktr_request *req; char *buf =3D NULL; size_t namelen; size_t buflen; if (!data) datalen =3D 0; namelen =3D strlen(name); buflen =3D namelen + 1 + datalen; buf =3D malloc(buflen, M_KTRACE, M_WAITOK); strcpy(buf, name); bcopy(data, buf + namelen + 1, datalen); if ((req =3D ktr_getrequest(KTR_STRUCT)) =3D=3D NULL) { free(buf, M_KTRACE); return; } req->ktr_buffer =3D buf; req->ktr_header.ktr_len =3D buflen; ktr_submitrequest(curthread, req); } --=20 You are receiving this mail because: You are the assignee for the bug.=