From owner-freebsd-bugs@freebsd.org Thu Feb 18 10:32:36 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 7AB3AAAC58E for ; Thu, 18 Feb 2016 10:32:36 +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 6056A968 for ; Thu, 18 Feb 2016 10:32:36 +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 u1IAWac0057331 for ; Thu, 18 Feb 2016 10:32:36 GMT (envelope-from bugzilla-noreply@freebsd.org) From: bugzilla-noreply@freebsd.org To: freebsd-bugs@FreeBSD.org Subject: [Bug 207302] Iconv uses strlen directly on user supplied memory Date: Thu, 18 Feb 2016 10:32:36 +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 Some People X-Bugzilla-Who: cturt@hardenedbsd.org 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: Thu, 18 Feb 2016 10:32:36 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D207302 Bug ID: 207302 Summary: Iconv uses strlen directly on user supplied memory Product: Base System Version: 11.0-CURRENT Hardware: Any OS: Any Status: New Severity: Affects Some People Priority: --- Component: kern Assignee: freebsd-bugs@FreeBSD.org Reporter: cturt@hardenedbsd.org `iconv_sysctl_add` from `sys/libkern/iconv.c` incorrectly limits the size of user strings, such that several out of bounds reads could have been possibl= e. static int iconv_sysctl_add(SYSCTL_HANDLER_ARGS) { struct iconv_converter_class *dcp; struct iconv_cspair *csp; struct iconv_add_in din; struct iconv_add_out dout; int error; error =3D SYSCTL_IN(req, &din, sizeof(din)); if (error) return error; if (din.ia_version !=3D ICONV_ADD_VER) return EINVAL; if (din.ia_datalen > ICONV_CSMAXDATALEN) return EINVAL; if (strlen(din.ia_from) >=3D ICONV_CSNMAXLEN) return EINVAL; if (strlen(din.ia_to) >=3D ICONV_CSNMAXLEN) return EINVAL; if (strlen(din.ia_converter) >=3D ICONV_CNVNMAXLEN) return EINVAL; ... Since the `din` struct is directly copied from userland, there is no guaran= tee that the strings supplied will be NULL terminated. The `strlen` calls could continue reading past the designated buffer sizes. Declaration of `struct iconv_add_in` is found in `sys/sys/iconv.h`: struct iconv_add_in { int ia_version; char ia_converter[ICONV_CNVNMAXLEN]; char ia_to[ICONV_CSNMAXLEN]; char ia_from[ICONV_CSNMAXLEN]; int ia_datalen; const void *ia_data; }; Our strings are followed by the `ia_datalen` member, which is checked before the `strlen` calls: if (din.ia_datalen > ICONV_CSMAXDATALEN) Since `ICONV_CSMAXDATALEN` has value `0x41000` (and is `unsigned`), this ensures that `din.ia_datalen` contains at least 1 byte of 0, so it is not possible to trigger a read out of bounds of the `struct` however, this code= is fragile and could introduce subtle bugs in the future if the `struct` is ev= er modified. --=20 You are receiving this mail because: You are the assignee for the bug.=