From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4644C350A04; Tue, 21 Oct 2025 19:52:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761076360; cv=none; b=b5awWNVvAfE+3Km6kXQ1Cv9aFaiRDxL0zJGIHRY/xsCEIi1OMYFQAFkblswZmXYQOSRSjUNriI8ttvec6z632mW+02eX4xufEVXIb3xq21giFR8z/L0VEIXtcn2KR+M3Hsci7yo1X+1BNNAwCc+bAeMXoTARwunkkiX4d0wRKdY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761076360; c=relaxed/simple; bh=rUjII1AsVsBh7I5cOyQdBoKFwL2hhVNY8xY+cSHasVw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=rHMCQRVHjXZcqR03N40l/8Ci4QYFCyr+yGCFHh8CswxdskW8cRwnrBhpqc2uq+r1Rl3Iw6SXXR7NJPiNDKrmQB3XGaFbxLZzkjKB2yO+OVVW7JKU/poC9vadSJ4QMr/4ui4A/jws60f4nhto8pZX95pr6Dk7vBZf4uGY58dvSbA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=VVofXK+T; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="VVofXK+T" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 508DBC4CEF1; Tue, 21 Oct 2025 19:52:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1761076360; bh=rUjII1AsVsBh7I5cOyQdBoKFwL2hhVNY8xY+cSHasVw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VVofXK+TUECwJSbKN3SOv5JVWb0hdDzMvfbgw9Zh7mAyofN3ci806BelpPUd40Jjm SXoQtOqBLcoj9XQIJhOhVH8/w5h4QvZYhjyl4+qCjUhUYYuZPdEyPDoB3IMM1tx/8L dOZgoqm0gg0cH60EpgYKaJFfWCXVSdZIp3DWUWzg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Oliver Upton , Marc Zyngier Subject: [PATCH 6.6 003/105] KVM: arm64: Prevent access to vCPU events before init Date: Tue, 21 Oct 2025 21:50:12 +0200 Message-ID: <20251021195021.576913624@linuxfoundation.org> X-Mailer: git-send-email 2.51.1 In-Reply-To: <20251021195021.492915002@linuxfoundation.org> References: <20251021195021.492915002@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Oliver Upton commit 0aa1b76fe1429629215a7c79820e4b96233ac4a3 upstream. Another day, another syzkaller bug. KVM erroneously allows userspace to pend vCPU events for a vCPU that hasn't been initialized yet, leading to KVM interpreting a bunch of uninitialized garbage for routing / injecting the exception. In one case the injection code and the hyp disagree on whether the vCPU has a 32bit EL1 and put the vCPU into an illegal mode for AArch64, tripping the BUG() in exception_target_el() during the next injection: kernel BUG at arch/arm64/kvm/inject_fault.c:40! Internal error: Oops - BUG: 00000000f2000800 [#1] SMP CPU: 3 UID: 0 PID: 318 Comm: repro Not tainted 6.17.0-rc4-00104-g10fd0285305d #6 PREEMPT Hardware name: linux,dummy-virt (DT) pstate: 21402009 (nzCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--) pc : exception_target_el+0x88/0x8c lr : pend_serror_exception+0x18/0x13c sp : ffff800082f03a10 x29: ffff800082f03a10 x28: ffff0000cb132280 x27: 0000000000000000 x26: 0000000000000000 x25: ffff0000c2a99c20 x24: 0000000000000000 x23: 0000000000008000 x22: 0000000000000002 x21: 0000000000000004 x20: 0000000000008000 x19: ffff0000c2a99c20 x18: 0000000000000000 x17: 0000000000000000 x16: 0000000000000000 x15: 00000000200000c0 x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000 x11: 0000000000000000 x10: 0000000000000000 x9 : 0000000000000000 x8 : ffff800082f03af8 x7 : 0000000000000000 x6 : 0000000000000000 x5 : ffff800080f621f0 x4 : 0000000000000000 x3 : 0000000000000000 x2 : 000000000040009b x1 : 0000000000000003 x0 : ffff0000c2a99c20 Call trace: exception_target_el+0x88/0x8c (P) kvm_inject_serror_esr+0x40/0x3b4 __kvm_arm_vcpu_set_events+0xf0/0x100 kvm_arch_vcpu_ioctl+0x180/0x9d4 kvm_vcpu_ioctl+0x60c/0x9f4 __arm64_sys_ioctl+0xac/0x104 invoke_syscall+0x48/0x110 el0_svc_common.constprop.0+0x40/0xe0 do_el0_svc+0x1c/0x28 el0_svc+0x34/0xf0 el0t_64_sync_handler+0xa0/0xe4 el0t_64_sync+0x198/0x19c Code: f946bc01 b4fffe61 9101e020 17fffff2 (d4210000) Reject the ioctls outright as no sane VMM would call these before KVM_ARM_VCPU_INIT anyway. Even if it did the exception would've been thrown away by the eventual reset of the vCPU's state. Cc: stable@vger.kernel.org # 6.17 Fixes: b7b27facc7b5 ("arm/arm64: KVM: Add KVM_GET/SET_VCPU_EVENTS") Signed-off-by: Oliver Upton Signed-off-by: Marc Zyngier Signed-off-by: Greg Kroah-Hartman --- arch/arm64/kvm/arm.c | 6 ++++++ 1 file changed, 6 insertions(+) --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -1492,6 +1492,9 @@ long kvm_arch_vcpu_ioctl(struct file *fi case KVM_GET_VCPU_EVENTS: { struct kvm_vcpu_events events; + if (!kvm_vcpu_initialized(vcpu)) + return -ENOEXEC; + if (kvm_arm_vcpu_get_events(vcpu, &events)) return -EINVAL; @@ -1503,6 +1506,9 @@ long kvm_arch_vcpu_ioctl(struct file *fi case KVM_SET_VCPU_EVENTS: { struct kvm_vcpu_events events; + if (!kvm_vcpu_initialized(vcpu)) + return -ENOEXEC; + if (copy_from_user(&events, argp, sizeof(events))) return -EFAULT;