From patchwork Mon Oct 27 18:56:16 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kamal Mostafa X-Patchwork-Id: 403814 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id 019F5140088; Tue, 28 Oct 2014 06:05:19 +1100 (AEDT) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1XipbN-0006fR-40; Mon, 27 Oct 2014 19:05:13 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1XipaQ-0005z8-Bv for kernel-team@lists.ubuntu.com; Mon, 27 Oct 2014 19:04:14 +0000 Received: from c-76-102-4-12.hsd1.ca.comcast.net ([76.102.4.12] helo=fourier) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1XipU4-0000ts-KY; Mon, 27 Oct 2014 18:57:40 +0000 Received: from kamal by fourier with local (Exim 4.82) (envelope-from ) id 1XipU2-0003hP-T4; Mon, 27 Oct 2014 11:57:38 -0700 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Subject: [PATCH 3.13 041/105] kvm: don't take vcpu mutex for obviously invalid vcpu ioctls Date: Mon, 27 Oct 2014 11:56:16 -0700 Message-Id: <1414436240-13879-42-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1414436240-13879-1-git-send-email-kamal@canonical.com> References: <1414436240-13879-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.13 Cc: David Matlack , Paolo Bonzini , Kamal Mostafa X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com 3.13.11.10 -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: Kamal Mostafa --- virt/kvm/kvm_main.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 44652f2..8d2a98a 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -52,6 +52,7 @@ #include #include +#include #include #include @@ -1994,6 +1995,9 @@ static long kvm_vcpu_ioctl(struct file *filp, 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,