Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760624AbYBFXMP (ORCPT ); Wed, 6 Feb 2008 18:12:15 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1763033AbYBFXHQ (ORCPT ); Wed, 6 Feb 2008 18:07:16 -0500 Received: from fk-out-0910.google.com ([209.85.128.190]:33939 "EHLO fk-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760670AbYBFXHH convert rfc822-to-8bit (ORCPT ); Wed, 6 Feb 2008 18:07:07 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=nxFFmOmO3+k4yUgzSAPaNf4LIv6Y5Wln1CzfUk0cGvMSojSyiR1ciASSmym8m+GDZKCTTHW3nfqhIEtttAIM9ckAwMZt7a1m8DT+CU2jOabwlHLctY+85mxP+RdmUpmTIidPWCgA3SlUiL5iGzSHzLVkoEx5dMVpuaX+yBxrTC8= Message-ID: <6101e8c40802061507x14ec503ubc7a9cd78304cfd0@mail.gmail.com> Date: Thu, 7 Feb 2008 00:07:04 +0100 From: "Oliver Pinter" To: "Linux Kernel" , stable@kernel.org, stable-commits@vger.kernel.org Subject: Re: [2.6.22.y] {06/17} - handle-bogus-%cs-selector-in-single-step-instruction-decoding - series for stable kernel #2 In-Reply-To: <6101e8c40802011733r40492c4fxa5ffd765504004fd@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Content-Disposition: inline References: <6101e8c40802011733r40492c4fxa5ffd765504004fd@mail.gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3241 Lines: 113 From: Roland McGrath Date: Mon, 16 Jul 2007 08:03:16 +0000 (-0700) Subject: Handle bogus %cs selector in single-step instruction decoding Patch-mainline: 2.6.23-rc1 References: 326270, CVE-2007-3731 Handle bogus %cs selector in single-step instruction decoding The code for LDT segment selectors was not robust in the face of a bogus selector set in %cs via ptrace before the single-step was done. Signed-off-by: Roland McGrath Signed-off-by: Linus Torvalds Acked-by: Jeff Mahoney --- arch/i386/kernel/ptrace.c | 22 +++++++++++++++------- arch/x86_64/kernel/ptrace.c | 23 ++++++++++++++++------- 2 files changed, 31 insertions(+), 14 deletions(-) diff --git a/arch/i386/kernel/ptrace.c b/arch/i386/kernel/ptrace.c index 1c075f5..0c8f00e 100644 --- a/arch/i386/kernel/ptrace.c +++ b/arch/i386/kernel/ptrace.c @@ -164,14 +164,22 @@ static unsigned long convert_eip_to_linear(struct task_struct *child, struct pt_ u32 *desc; unsigned long base; - down(&child->mm->context.sem); - desc = child->mm->context.ldt + (seg & ~7); - base = (desc[0] >> 16) | ((desc[1] & 0xff) << 16) | (desc[1] & 0xff000000); + seg &= ~7UL; - /* 16-bit code segment? */ - if (!((desc[1] >> 22) & 1)) - addr &= 0xffff; - addr += base; + down(&child->mm->context.sem); + if (unlikely((seg >> 3) >= child->mm->context.size)) + addr = -1L; /* bogus selector, access would fault */ + else { + desc = child->mm->context.ldt + seg; + base = ((desc[0] >> 16) | + ((desc[1] & 0xff) << 16) | + (desc[1] & 0xff000000)); + + /* 16-bit code segment? */ + if (!((desc[1] >> 22) & 1)) + addr &= 0xffff; + addr += base; + } up(&child->mm->context.sem); } return addr; diff --git a/arch/x86_64/kernel/ptrace.c b/arch/x86_64/kernel/ptrace.c index fa6775e..e83cc67 100644 --- a/arch/x86_64/kernel/ptrace.c +++ b/arch/x86_64/kernel/ptrace.c @@ -102,16 +102,25 @@ unsigned long convert_rip_to_linear(struct task_struct *child, struct pt_regs *r u32 *desc; unsigned long base; - down(&child->mm->context.sem); - desc = child->mm->context.ldt + (seg & ~7); - base = (desc[0] >> 16) | ((desc[1] & 0xff) << 16) | (desc[1] & 0xff000000); + seg &= ~7UL; - /* 16-bit code segment? */ - if (!((desc[1] >> 22) & 1)) - addr &= 0xffff; - addr += base; + down(&child->mm->context.sem); + if (unlikely((seg >> 3) >= child->mm->context.size)) + addr = -1L; /* bogus selector, access would fault */ + else { + desc = child->mm->context.ldt + seg; + base = ((desc[0] >> 16) | + ((desc[1] & 0xff) << 16) | + (desc[1] & 0xff000000)); + + /* 16-bit code segment? */ + if (!((desc[1] >> 22) & 1)) + addr &= 0xffff; + addr += base; + } up(&child->mm->context.sem); } + return addr; } On 2/2/08, Oliver Pinter (Pint?r Oliv?r) wrote: > mainline: 29eb51101c02df517ca64ec472d7501127ad1da8 > > > -- > Thanks, > Oliver > -- Thanks, Oliver -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/