From patchwork Fri Apr 19 10:29:21 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marc Zyngier X-Patchwork-Id: 13636195 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 B45A9C071DB for ; Fri, 19 Apr 2024 10:30:27 +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=uhgNcPoQZxSzEbh8xj7IVnkV/bJcvtlje4aKhsPIoBA=; b=R0mMLF7t1MoKkc 6UCc0sEJoSBM7qzDBkGAkL+8cDT+suQK74pqQL/rrFXdm3Vga8lAFuYBU3Xx/q2ehJIM/P8QBTa2H rkVi/CpAnvnnNTceK1fgAV/2P7dSsW7MEGmA3NfVZ+KU/JfNCIQ0OsV5jwyTpJzhW0W0XLGFFGBfi NipkkQgfvuDdYd1VaVC18ODhDKK33AJEmD6mBnEVTXbQKsSar3jBtiF8CtyrplkSowo40/Mcf+pKe 9LEHfvdtua1Q2edJZOpWn4OaQHgXjpBVvy8nV3q0XgwpQybyhJ/QPcYVXH4Gy4t8r4S+15sjCuHLI LbaslVdSVXWSontB0YuA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1rxlVU-00000005J1q-0rRY; Fri, 19 Apr 2024 10:30:12 +0000 Received: from sin.source.kernel.org ([2604:1380:40e1:4800::1]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1rxlVC-00000005Ioe-0871 for linux-arm-kernel@lists.infradead.org; Fri, 19 Apr 2024 10:29:56 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sin.source.kernel.org (Postfix) with ESMTP id 3D58BCE1A55; Fri, 19 Apr 2024 10:29:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6A176C32781; Fri, 19 Apr 2024 10:29:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1713522591; bh=KNYLgx5NhqQdD7ul1Nk1kGdw1Hv2DXSeVOrfdXxsuXs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fDuGnBKtC2U4IEzyzQSDCnCr2TOZ9imLo9b31T4hS2iCG/hdPbCcYMbQWLmavFbj9 RhH4n9IqCyfkTIqd3SMvC/KuLpbhXzBtPvvEPivEPODcOjp/Dr5haIj+71jcl0Oc1U LQPLFypo/8krnycZbVp4oENnQYYjx2U62yoopxA01aUJ5Iakt9rH+SUEMON0XH2cyP Z/olyfyDN1BPhUh1FQGw27w0Jhxpo/2Tk4HtZ/q7KTDevEWK9UIiKNl5sbMalWnZ1q sxpv6n1vGKudhMkXHg8JhQZ6DVyNb0znTKliTw7MO9azokV9R/sNiDbFkQJ4VExRR1 xHLF8EzHAewsg== 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 1rxlV7-00636W-4i; Fri, 19 Apr 2024 11:29:49 +0100 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 , Joey Gouly , Fuad Tabba , Mostafa Saleh , Will Deacon , Catalin Marinas Subject: [PATCH v4 01/15] KVM: arm64: Harden __ctxt_sys_reg() against out-of-range values Date: Fri, 19 Apr 2024 11:29:21 +0100 Message-Id: <20240419102935.1935571-2-maz@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20240419102935.1935571-1-maz@kernel.org> References: <20240419102935.1935571-1-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, joey.gouly@arm.com, tabba@google.com, smostafa@google.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-20240419_032954_452890_F57C4076 X-CRM114-Status: GOOD ( 12.92 ) 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: , 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. Reviewed-by: Joey Gouly 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 9e8a496fb284..e24bd876ec9a 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -896,7 +896,7 @@ 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) && @@ -906,6 +906,13 @@ 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);