lkml.org 
[lkml]   [2017]   [Feb]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [PATCH 4/4] kvm: convert kvm.users_count from atomic_t to refcount_t
    From
    Date
    On 20/02/2017 12:06, Elena Reshetova wrote:
    > refcount_t type and corresponding API should be
    > used instead of atomic_t when the variable is used as
    > a reference counter. This allows to avoid accidental
    > refcounter overflows that might lead to use-after-free
    > situations.
    >
    > Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
    > Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
    > Signed-off-by: Kees Cook <keescook@chromium.org>
    > Signed-off-by: David Windsor <dwindsor@gmail.com>

    Looks good, will apply after the merge window.

    Paolo

    > ---
    > include/linux/kvm_host.h | 3 ++-
    > virt/kvm/kvm_main.c | 8 ++++----
    > 2 files changed, 6 insertions(+), 5 deletions(-)
    >
    > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
    > index cda457b..7fa05a5 100644
    > --- a/include/linux/kvm_host.h
    > +++ b/include/linux/kvm_host.h
    > @@ -26,6 +26,7 @@
    > #include <linux/context_tracking.h>
    > #include <linux/irqbypass.h>
    > #include <linux/swait.h>
    > +#include <linux/refcount.h>
    > #include <asm/signal.h>
    >
    > #include <linux/kvm.h>
    > @@ -402,7 +403,7 @@ struct kvm {
    > #endif
    > struct kvm_vm_stat stat;
    > struct kvm_arch arch;
    > - atomic_t users_count;
    > + refcount_t users_count;
    > #ifdef KVM_COALESCED_MMIO_PAGE_OFFSET
    > struct kvm_coalesced_mmio_ring *coalesced_mmio_ring;
    > spinlock_t ring_lock;
    > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
    > index dcd1c12..6ae5775 100644
    > --- a/virt/kvm/kvm_main.c
    > +++ b/virt/kvm/kvm_main.c
    > @@ -622,7 +622,7 @@ static struct kvm *kvm_create_vm(unsigned long type)
    > mutex_init(&kvm->lock);
    > mutex_init(&kvm->irq_lock);
    > mutex_init(&kvm->slots_lock);
    > - atomic_set(&kvm->users_count, 1);
    > + refcount_set(&kvm->users_count, 1);
    > INIT_LIST_HEAD(&kvm->devices);
    >
    > r = kvm_arch_init_vm(kvm, type);
    > @@ -745,13 +745,13 @@ static void kvm_destroy_vm(struct kvm *kvm)
    >
    > void kvm_get_kvm(struct kvm *kvm)
    > {
    > - atomic_inc(&kvm->users_count);
    > + refcount_inc(&kvm->users_count);
    > }
    > EXPORT_SYMBOL_GPL(kvm_get_kvm);
    >
    > void kvm_put_kvm(struct kvm *kvm)
    > {
    > - if (atomic_dec_and_test(&kvm->users_count))
    > + if (refcount_dec_and_test(&kvm->users_count))
    > kvm_destroy_vm(kvm);
    > }
    > EXPORT_SYMBOL_GPL(kvm_put_kvm);
    > @@ -3640,7 +3640,7 @@ static int kvm_debugfs_open(struct inode *inode, struct file *file,
    > * To avoid the race between open and the removal of the debugfs
    > * directory we test against the users count.
    > */
    > - if (!atomic_add_unless(&stat_data->kvm->users_count, 1, 0))
    > + if (!refcount_inc_not_zero(&stat_data->kvm->users_count))
    > return -ENOENT;
    >
    > if (simple_attr_open(inode, file, get, set, fmt)) {
    >

    \
     
     \ /
      Last update: 2017-02-20 12:37    [W:4.045 / U:0.084 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site