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KVM: fix irqfd assign/deassign race 

I think I see the following (theoretical) race:

During irqfd assign, we drop irqfds lock before we
schedule inject work. Therefore, deassign running
on another CPU could cause shutdown and flush to run
before inject, causing user after free in inject.

A simple fix it to schedule inject under the lock.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Gregory Haskins <ghaskins@novell.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Michael S. Tsirkin 2010-09-19 19:02:31 +02:00 committed by Marcelo Tosatti
parent c79bd89282
commit 6bbfb26531
1 changed files with 2 additions and 1 deletions
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3
virt/kvm/eventfd.c
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@ -218,7 +218,6 @@ kvm_irqfd_assign(struct kvm *kvm, int fd, int gsi)
events = file->f_op->poll(file, &irqfd->pt);
list_add_tail(&irqfd->list, &kvm->irqfds.items);
spin_unlock_irq(&kvm->irqfds.lock);
/*
* Check if there was an event already pending on the eventfd
@ -227,6 +226,8 @@ kvm_irqfd_assign(struct kvm *kvm, int fd, int gsi)
if (events & POLLIN)
schedule_work(&irqfd->inject);
spin_unlock_irq(&kvm->irqfds.lock);
/*
* do not drop the file until the irqfd is fully initialized, otherwise
* we might race against the POLLHUP