Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751933AbaL3W1N (ORCPT ); Tue, 30 Dec 2014 17:27:13 -0500 Received: from mail-wg0-f41.google.com ([74.125.82.41]:45305 "EHLO mail-wg0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751461AbaL3W1M convert rfc822-to-8bit (ORCPT ); Tue, 30 Dec 2014 17:27:12 -0500 Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 8.1 \(1993\)) Subject: Re: [PATCH 3.13 106/162] KVM: x86: Fix far-jump to non-canonical check From: Nadav Amit In-Reply-To: Date: Wed, 31 Dec 2014 00:27:07 +0200 Cc: Kamal Mostafa , LKML , stable@vger.kernel.org, kernel-team@lists.ubuntu.com, Nadav Amit , Paolo Bonzini Content-Transfer-Encoding: 8BIT Message-Id: References: <1415313426-9622-1-git-send-email-kamal@canonical.com> <1415313426-9622-107-git-send-email-kamal@canonical.com> To: Vinson Lee X-Mailer: Apple Mail (2.1993) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Vinson Lee wrote: > On Thu, Nov 6, 2014 at 2:36 PM, Kamal Mostafa wrote: >> 3.13.11.11 -stable review patch. If anyone has any objections, please let me know. >> >> ------------------ >> >> From: Nadav Amit >> >> commit 7e46dddd6f6cd5dbf3c7bd04a7e75d19475ac9f2 upstream. >> >> Commit d1442d85cc30 ("KVM: x86: Handle errors when RIP is set during far >> jumps") introduced a bug that caused the fix to be incomplete. Due to >> incorrect evaluation, far jump to segment with L bit cleared (i.e., 32-bit >> segment) and RIP with any of the high bits set (i.e, RIP[63:32] != 0) set may >> not trigger #GP. As we know, this imposes a security problem. >> >> In addition, the condition for two warnings was incorrect. >> >> Fixes: d1442d85cc30ea75f7d399474ca738e0bc96f715 >> Reported-by: Dan Carpenter >> Signed-off-by: Nadav Amit >> [Add #ifdef CONFIG_X86_64 to avoid complaints of undefined behavior. - Paolo] >> Signed-off-by: Paolo Bonzini >> [ kamal: backport to 3.13-stable: omitted WARN_ON fixes (not in 3.13) ] >> Signed-off-by: Kamal Mostafa >> --- >> arch/x86/kvm/emulate.c | 4 +++- >> 1 file changed, 3 insertions(+), 1 deletion(-) >> >> diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c >> index a440bea..4ae37e7 100644 >> --- a/arch/x86/kvm/emulate.c >> +++ b/arch/x86/kvm/emulate.c >> @@ -581,12 +581,14 @@ static inline int assign_eip_far(struct x86_emulate_ctxt *ctxt, ulong dst, >> case 4: >> ctxt->_eip = (u32)dst; >> break; >> +#ifdef CONFIG_X86_64 >> case 8: >> if ((cs_l && is_noncanonical_address(dst)) || >> - (!cs_l && (dst & ~(u32)-1))) >> + (!cs_l && (dst >> 32) != 0)) >> return emulate_gp(ctxt, 0); >> ctxt->_eip = dst; >> break; >> +#endif >> default: >> WARN(1, "unsupported eip assignment size\n"); >> } >> -- >> 1.9.1 >> >> -- >> To unsubscribe from this list: send the line "unsubscribe stable" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html > > > Hi. > > Should the WARN_ON fixes have been included as well in 3.13.11.11? > > WARN_ON hunks were added with the backport of "KVM: x86: Handle errors > when RIP is set during far jumps" in 3.13.11.11 commit > b8ba339d86fb627d54fea929492114d45f6835c2. If it was added, it should be fixed. The WARN_ON mistakenly has double-negation. Nadav -- 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/