From nobody Fri Nov 14 18:06:32 2025 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1760814495129123.29382611269921; Sat, 18 Oct 2025 12:08:15 -0700 (PDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vACH8-0006Vi-Nz; Sat, 18 Oct 2025 15:07:35 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vACH0-0006QO-I3; Sat, 18 Oct 2025 15:07:30 -0400 Received: from isrv.corpit.ru ([212.248.84.144]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vACGw-00010X-Gs; Sat, 18 Oct 2025 15:07:26 -0400 Received: from tsrv.corpit.ru (tsrv.tls.msk.ru [192.168.177.2]) by isrv.corpit.ru (Postfix) with ESMTP id BD34D15F79C; Sat, 18 Oct 2025 22:06:58 +0300 (MSK) Received: from think4mjt.tls.msk.ru (mjtthink.wg.tls.msk.ru [192.168.177.146]) by tsrv.corpit.ru (Postfix) with ESMTP id 83EF32F0605; Sat, 18 Oct 2025 22:07:02 +0300 (MSK) From: Michael Tokarev To: qemu-devel@nongnu.org Cc: qemu-stable@nongnu.org, Paolo Bonzini , YiFei Zhu , Michael Tokarev Subject: [Stable-10.1.2 15/23] i386/cpu: Prevent delivering SIPI during SMM in TCG mode Date: Sat, 18 Oct 2025 22:06:50 +0300 Message-ID: <20251018190702.1178893-4-mjt@tls.msk.ru> X-Mailer: git-send-email 2.47.3 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=212.248.84.144; envelope-from=mjt@tls.msk.ru; helo=isrv.corpit.ru X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZM-MESSAGEID: 1760814503266158500 Content-Type: text/plain; charset="utf-8" From: Paolo Bonzini [commit message by YiFei Zhu] A malicious kernel may control the instruction pointer in SMM in a multi-processor VM by sending a sequence of IPIs via APIC: CPU0 CPU1 IPI(CPU1, MODE_INIT) x86_cpu_exec_reset() apic_init_reset() s->wait_for_sipi =3D true IPI(CPU1, MODE_SMI) do_smm_enter() env->hflags |=3D HF_SMM_MASK; IPI(CPU1, MODE_STARTUP, vector) do_cpu_sipi() apic_sipi() /* s->wait_for_sipi check passes */ cpu_x86_load_seg_cache_sipi(vector) A different sequence, SMI INIT SIPI, is also buggy in TCG because INIT is not blocked or latched during SMM. However, it is not vulnerable to an instruction pointer control in the same way because x86_cpu_exec_reset clears env->hflags, exiting SMM. Fixes: a9bad65d2c1f ("target-i386: wake up processors that receive an SMI") Analyzed-by: YiFei Zhu Cc: qemu-stable@nongnu.org Signed-off-by: Paolo Bonzini (cherry picked from commit df32e5c568c9cf68c15a9bbd98d0c3aff19eab63) Signed-off-by: Michael Tokarev diff --git a/hw/intc/apic.c b/hw/intc/apic.c index bcb103560c..143d08f1aa 100644 --- a/hw/intc/apic.c +++ b/hw/intc/apic.c @@ -645,8 +645,6 @@ void apic_sipi(DeviceState *dev) { APICCommonState *s =3D APIC(dev); =20 - cpu_reset_interrupt(CPU(s->cpu), CPU_INTERRUPT_SIPI); - if (!s->wait_for_sipi) return; cpu_x86_load_seg_cache_sipi(s->cpu, s->sipi_vector); diff --git a/target/i386/helper.c b/target/i386/helper.c index e0aaed3c4c..693a95558f 100644 --- a/target/i386/helper.c +++ b/target/i386/helper.c @@ -619,6 +619,10 @@ void do_cpu_init(X86CPU *cpu) =20 void do_cpu_sipi(X86CPU *cpu) { + CPUX86State *env =3D &cpu->env; + if (env->hflags & HF_SMM_MASK) { + return; + } apic_sipi(cpu->apic_state); } =20 diff --git a/target/i386/tcg/system/seg_helper.c b/target/i386/tcg/system/s= eg_helper.c index d4ea890c12..e7d76e41d2 100644 --- a/target/i386/tcg/system/seg_helper.c +++ b/target/i386/tcg/system/seg_helper.c @@ -182,6 +182,7 @@ bool x86_cpu_exec_interrupt(CPUState *cs, int interrupt= _request) apic_poll_irq(cpu->apic_state); break; case CPU_INTERRUPT_SIPI: + cpu_reset_interrupt(cs, CPU_INTERRUPT_SIPI); do_cpu_sipi(cpu); break; case CPU_INTERRUPT_SMI: --=20 2.47.3