Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754492AbaKKLzF (ORCPT ); Tue, 11 Nov 2014 06:55:05 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:57381 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753846AbaKKLJz (ORCPT ); Tue, 11 Nov 2014 06:09:55 -0500 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Nadav Amit , Paolo Bonzini , Luis Henriques Subject: [PATCH 3.16.y-ckt 057/170] KVM: x86: Fix far-jump to non-canonical check Date: Tue, 11 Nov 2014 11:06:56 +0000 Message-Id: <1415704129-12709-58-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 2.1.0 In-Reply-To: <1415704129-12709-1-git-send-email-luis.henriques@canonical.com> References: <1415704129-12709-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.16 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.7-ckt1 -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 Signed-off-by: Luis Henriques --- arch/x86/kvm/emulate.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 9a1946cb43c8..bcb3134a8d4c 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -582,12 +582,14 @@ 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"); } @@ -1998,7 +2000,7 @@ static int em_jmp_far(struct x86_emulate_ctxt *ctxt) rc = assign_eip_far(ctxt, ctxt->src.val, new_desc.l); if (rc != X86EMUL_CONTINUE) { - WARN_ON(!ctxt->mode != X86EMUL_MODE_PROT64); + WARN_ON(ctxt->mode != X86EMUL_MODE_PROT64); /* assigning eip failed; restore the old cs */ ops->set_segment(ctxt, old_sel, &old_desc, 0, VCPU_SREG_CS); return rc; @@ -2092,7 +2094,7 @@ static int em_ret_far(struct x86_emulate_ctxt *ctxt) return rc; rc = assign_eip_far(ctxt, eip, new_desc.l); if (rc != X86EMUL_CONTINUE) { - WARN_ON(!ctxt->mode != X86EMUL_MODE_PROT64); + WARN_ON(ctxt->mode != X86EMUL_MODE_PROT64); ops->set_segment(ctxt, old_cs, &old_desc, 0, VCPU_SREG_CS); } return rc; -- 2.1.0 -- 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/