linux-kernel - [PATCH 3.10 07/43] kvm: dont take vcpu mutex for obviously invalid vcpu ioctls

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20141028033523.723554669@linuxfoundation.org>
Date:	Tue, 28 Oct 2014 11:36:05 +0800
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, David Matlack <dmatlack@...gle.com>,
	Paolo Bonzini <pbonzini@...hat.com>
Subject: [PATCH 3.10 07/43] kvm: dont take vcpu mutex for obviously invalid vcpu ioctls

3.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: David Matlack <dmatlack@...gle.com>

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 <dmatlack@...gle.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 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 <asm/processor.h>
 #include <asm/io.h>
+#include <asm/ioctl.h>
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
 
@@ -1981,6 +1982,9 @@ 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@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/