KVM: kvm_io_bus_unregister_dev() should never fail

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commit 90db10434b upstream.

No caller currently checks the return value of
kvm_io_bus_unregister_dev(). This is evil, as all callers silently go on
freeing their device. A stale reference will remain in the io_bus,
getting at least used again, when the iobus gets teared down on
kvm_destroy_vm() - leading to use after free errors.

There is nothing the callers could do, except retrying over and over
again.

So let's simply remove the bus altogether, print an error and make
sure no one can access this broken bus again (returning -ENOMEM on any
attempt to access it).

Fixes: e93f8a0f82 ("KVM: convert io_bus to SRCU")
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

This commit is contained in:

David Hildenbrand 2017-03-23 18:24:19 +01:00 • committed by Greg Kroah-Hartman

parent c6216a0f1e

commit 07882feab4

3 changed files with 27 additions and 20 deletions

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4

include/linux/kvm_host.h

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3

virt/kvm/eventfd.c

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40

virt/kvm/kvm_main.c

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