path: root/virt
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authorDavid Matlack <dmatlack@google.com>2014-09-19 16:03:25 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-10-30 09:35:10 -0700
commit7889ddde2798154828d49da8d7c8863b7573e62d (patch)
treeadb87dd764ad618946e095d58819a7581f764d32 /virt
parent68249f03d07ff212ee1b0170450985d896378f88 (diff)
kvm: don't take vcpu mutex for obviously invalid vcpu ioctls
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@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'virt')
1 files changed, 4 insertions, 0 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 8cf1cd2fadaa..a17f190be58e 100644
--- 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 *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,