From owner-freebsd-bugs@freebsd.org Sun Jan 24 00:13:59 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 21E2DA8FEAB for ; Sun, 24 Jan 2016 00:13:59 +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 ED0CD1FBB for ; Sun, 24 Jan 2016 00:13:58 +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 u0O0DwGU028444 for ; Sun, 24 Jan 2016 00:13:58 GMT (envelope-from bugzilla-noreply@freebsd.org) From: bugzilla-noreply@freebsd.org To: freebsd-bugs@FreeBSD.org Subject: [Bug 206551] Integer overflow in iconv kernel module Date: Sun, 24 Jan 2016 00:13:59 +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 Only Me X-Bugzilla-Who: ertl.chris@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: Sun, 24 Jan 2016 00:13:59 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D206551 Bug ID: 206551 Summary: Integer overflow in iconv kernel module Product: Base System Version: 11.0-CURRENT Hardware: Any OS: Any Status: New Severity: Affects Only Me Priority: --- Component: kern Assignee: freebsd-bugs@FreeBSD.org Reporter: ertl.chris@gmail.com After loading the iconv kernel module, a new sysctl name, "kern.iconv.add" = is accessible for `root` user. This is handled with the following code: static int iconv_sysctl_add(SYSCTL_HANDLER_ARGS) { ... if (din.ia_datalen > ICONV_CSMAXDATALEN) return EINVAL; ... if (din.ia_datalen) { csp->cp_data =3D malloc(din.ia_datalen, M_ICONVDATA, M_WAITOK); error =3D copyin(din.ia_data, csp->cp_data, din.ia_datalen); if (error) goto bad; } ... } Since the `ia_datalen` member of `struct iconv_add_in` is signed: 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; }; The check on user supplied `din.ia_datalen` is insufficient. If a negative value is passed, it will bypass the check, and then wraparound to a huge va= lue when converted to an `unsigned` type to be passed to `malloc` and `copyin`.= For example, passing `-1` will bypass the check, and then attempt to allocate a= nd copy to a buffer of size `0xffffffff`. The impact of this is low, since it is only triggerable as `root`, and coul= d at most result in DoS. The solution is to replace this check: if (din.ia_datalen > ICONV_CSMAXDATALEN) With this: if (din.ia_datalen > ICONV_CSMAXDATALEN || din.ia_datalen < 0) --=20 You are receiving this mail because: You are the assignee for the bug.=