From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C6E79C54766 for ; Mon, 19 Feb 2024 09:21:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=Gp/nQbuzk1KMNNUcoK+HG2YA5tI70OK4idqmtGCLZHk=; b=5AsTQMXgCdicC7 3H/KIVDIZQo/wQpXu6c3c8jndUKnssgJ4AYaeVRErhbIly7VLfI+W/GDPqtVuhmW4jiQJSpOPpVKo 2sHm5B+EEdsEnshPoDrZjAbeJ0j6MIq6QAU48Swy7pvEgpy9cKVipxiQSEeIo6Qu6d1s5rfam2pfh 9mgceJAVASAPXW/gic1CmB+sTN+soo9V/O00JUdlIQo7EqhnZpgiNBnnP++lRFmV+tJ1F1EjtmCdC oZzV/VNxSuhx++ZdQP8H4Br4CUfLoXpkvmdFjDjytFuU2fzRIZh5kLdE1fmP3YwQmi+sMDkUElH2l XHL3Y1CQvFg3HV2Yz6ew==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1rbzph-00000009mMA-26j0; Mon, 19 Feb 2024 09:21:05 +0000 Received: from sin.source.kernel.org ([145.40.73.55]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1rbzp4-00000009lxG-2jKM for linux-arm-kernel@lists.infradead.org; Mon, 19 Feb 2024 09:20:29 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sin.source.kernel.org (Postfix) with ESMTP id DD5EACE10B4; Mon, 19 Feb 2024 09:20:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 02A69C43390; Mon, 19 Feb 2024 09:20:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1708334424; bh=KX/oVgZNALTsrMNLjBJoW2oz/1yIUZB9MBfcJb7mNbQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=a1m0F4hiVbx60dhNCFW8c2yNdImKotiMvh6LmS9qtwB936taQ68HNw8O97prLYBiQ uhcKz2iLT67C+vAsLRIeV31JLgMK3FHNGzvTMrzZ7hb8YsbAWaW0sMArdv4QT/BKXE 79LMyUX/BZnrPrEH0rDznlWEGq38MA+VPs/IDOjwwGGUYt4EpV2Rw7KdopX+dNlYkw ku3JDoa9Y1vZ80u5YbEev7d4k8JfJAExN6Eaqef/H6Xvak+3oHx3Gu+TdMLs0LXk2N PJ6iBt8n9lkCXW1EuDibUMcOlnwD0HQIoGgYbo3CMoFJsT9BbB2eMSrb2Pbqd4lMnl 6Zihn4Hi53CIQ== Received: from sofa.misterjones.org ([185.219.108.64] helo=valley-girl.lan) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1rbzoz-004WBZ-Jb; Mon, 19 Feb 2024 09:20:21 +0000 From: Marc Zyngier To: kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: James Morse , Suzuki K Poulose , Oliver Upton , Zenghui Yu , Will Deacon , Catalin Marinas Subject: [PATCH 01/13] KVM: arm64: Harden __ctxt_sys_reg() against out-of-range values Date: Mon, 19 Feb 2024 09:20:02 +0000 Message-Id: <20240219092014.783809-2-maz@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20240219092014.783809-1-maz@kernel.org> References: <20240219092014.783809-1-maz@kernel.org> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, james.morse@arm.com, suzuki.poulose@arm.com, oliver.upton@linux.dev, yuzenghui@huawei.com, will@kernel.org, catalin.marinas@arm.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240219_012027_180642_4B210CFA X-CRM114-Status: GOOD ( 12.29 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org The unsuspecting kernel tinkerer can be easily confused into writing something that looks like this: ikey.lo = __vcpu_sys_reg(vcpu, SYS_APIAKEYLO_EL1); which seems vaguely sensible, until you realise that the second parameter is the encoding of a sysreg, and not the index into the vcpu sysreg file... Debugging what happens in this case is an interesting exercise in head<->wall interactions. As they often say: "Any resemblance to actual persons, living or dead, or actual events is purely coincidental". In order to save people's time, add some compile-time hardening that will at least weed out the "stupidly out of range" values. This will *not* catch anything that isn't a compile-time constant. Signed-off-by: Marc Zyngier --- arch/arm64/include/asm/kvm_host.h | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 181fef12e8e8..a5ec4c7d3966 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -895,7 +895,7 @@ struct kvm_vcpu_arch { * Don't bother with VNCR-based accesses in the nVHE code, it has no * business dealing with NV. */ -static inline u64 *__ctxt_sys_reg(const struct kvm_cpu_context *ctxt, int r) +static inline u64 *___ctxt_sys_reg(const struct kvm_cpu_context *ctxt, int r) { #if !defined (__KVM_NVHE_HYPERVISOR__) if (unlikely(cpus_have_final_cap(ARM64_HAS_NESTED_VIRT) && @@ -905,6 +905,13 @@ static inline u64 *__ctxt_sys_reg(const struct kvm_cpu_context *ctxt, int r) return (u64 *)&ctxt->sys_regs[r]; } +#define __ctxt_sys_reg(c,r) \ + ({ \ + BUILD_BUG_ON(__builtin_constant_p(r) && \ + (r) >= NR_SYS_REGS); \ + ___ctxt_sys_reg(c, r); \ + }) + #define ctxt_sys_reg(c,r) (*__ctxt_sys_reg(c,r)) u64 kvm_vcpu_sanitise_vncr_reg(const struct kvm_vcpu *, enum vcpu_sysreg); -- 2.39.2 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel