Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965995AbaLLGsQ (ORCPT ); Fri, 12 Dec 2014 01:48:16 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:52598 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759235AbaLLGsK (ORCPT ); Fri, 12 Dec 2014 01:48:10 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "David Matlack" , "Paolo Bonzini" Date: Fri, 12 Dec 2014 06:14:25 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 028/164] kvm: don't take vcpu mutex for obviously invalid vcpu ioctls In-Reply-To: X-SA-Exim-Connect-IP: 2001:470:1f08:1539:c97:8151:cc89:c28d X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.65-rc1 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 [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings --- 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 @@ -1766,6 +1767,9 @@ 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) /* * 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/