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KVM: kill file->f_count abuse in kvm

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Use kvm own refcounting instead of playing with ->filp->f_count.
That will allow to get rid of a lot of crap in anon_inode_getfd() and
kill a race in kvm_dev_ioctl_create_vm() (file might have been closed
immediately by another thread, so ->filp might point to already freed
struct file when we get around to setting it).

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Avi Kivity <avi@qumranet.com>
This commit is contained in:
Al Viro 2008-04-19 20:33:56 +01:00 committed by Avi Kivity
parent 960b399169
commit 66c0b394f0
2 changed files with 6 additions and 7 deletions
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1
include/linux/kvm_host.h
View file

@ -110,7 +110,6 @@ struct kvm {
KVM_PRIVATE_MEM_SLOTS];
struct kvm_vcpu *vcpus[KVM_MAX_VCPUS];
struct list_head vm_list;
struct file *filp;
struct kvm_io_bus mmio_bus;
struct kvm_io_bus pio_bus;
struct kvm_vm_stat stat;

12
virt/kvm/kvm_main.c
View file

@ -818,7 +818,7 @@ static int kvm_vcpu_release(struct inode *inode, struct file *filp)
{
struct kvm_vcpu *vcpu = filp->private_data;
fput(vcpu->kvm->filp);
kvm_put_kvm(vcpu->kvm);
return 0;
}
@ -840,9 +840,10 @@ static int create_vcpu_fd(struct kvm_vcpu *vcpu)
r = anon_inode_getfd(&fd, &inode, &file,
"kvm-vcpu", &kvm_vcpu_fops, vcpu);
if (r)
if (r) {
kvm_put_kvm(vcpu->kvm);
return r;
atomic_inc(&vcpu->kvm->filp->f_count);
}
return fd;
}
@ -877,6 +878,7 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, int n)
mutex_unlock(&kvm->lock);
/* Now it's all set up, let userspace reach it */
kvm_get_kvm(kvm);
r = create_vcpu_fd(vcpu);
if (r < 0)
goto unlink;
@ -1176,12 +1178,10 @@ static int kvm_dev_ioctl_create_vm(void)
return PTR_ERR(kvm);
r = anon_inode_getfd(&fd, &inode, &file, "kvm-vm", &kvm_vm_fops, kvm);
if (r) {
kvm_destroy_vm(kvm);
kvm_put_kvm(kvm);
return r;
}
kvm->filp = file;
return fd;
}