Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753996AbaJ1Dh0 (ORCPT ); Mon, 27 Oct 2014 23:37:26 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:44403 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753766AbaJ1DhW (ORCPT ); Mon, 27 Oct 2014 23:37:22 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, David Matlack , Paolo Bonzini Subject: [PATCH 3.17 020/146] kvm: dont take vcpu mutex for obviously invalid vcpu ioctls Date: Tue, 28 Oct 2014 11:32:42 +0800 Message-Id: <20141028033344.300833735@linuxfoundation.org> X-Mailer: git-send-email 2.1.2 In-Reply-To: <20141028033343.441992423@linuxfoundation.org> References: <20141028033343.441992423@linuxfoundation.org> User-Agent: quilt/0.63-1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.17-stable review patch. If anyone has any objections, please let me know. ------------------ From: David Matlack commit 2ea75be3219571d0ec009ce20d9971e54af96e09 upstream. vcpu ioctls can hang the calling thread if issued while a vcpu is running. However, invalid ioctls can happen when userspace tries to probe the kind of file descriptors (e.g. isatty() calls ioctl(TCGETS)); in that case, we know the ioctl is going to be rejected as invalid anyway and we can fail before trying to take the vcpu mutex. This patch does not change functionality, it just makes invalid ioctls fail faster. Signed-off-by: David Matlack Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- virt/kvm/kvm_main.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -52,6 +52,7 @@ #include #include +#include #include #include @@ -1991,6 +1992,9 @@ static long kvm_vcpu_ioctl(struct file * if (vcpu->kvm->mm != current->mm) return -EIO; + if (unlikely(_IOC_TYPE(ioctl) != KVMIO)) + return -EINVAL; + #if defined(CONFIG_S390) || defined(CONFIG_PPC) || defined(CONFIG_MIPS) /* * Special cases: vcpu ioctls that are asynchronous to vcpu execution, -- 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/