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be8d3adae6
Without locking userspace can trigger a UAF by racing
KVM_DEV_VFIO_GROUP_DEL with VFIO_GROUP_GET_DEVICE_FD:
CPU1 CPU2
ioctl(KVM_DEV_VFIO_GROUP_DEL)
ioctl(VFIO_GROUP_GET_DEVICE_FD)
vfio_group_get_device_fd
open_device()
intel_vgpu_open_device()
vfio_register_notifier()
vfio_register_group_notifier()
blocking_notifier_call_chain(&group->notifier,
VFIO_GROUP_NOTIFY_SET_KVM, group->kvm);
set_kvm()
group->kvm = NULL
close()
kfree(kvm)
intel_vgpu_group_notifier()
vdev->kvm = data
[..]
kvm_get_kvm(vgpu->kvm);
// UAF!
Add a simple rwsem in the group to protect the kvm while the notifier is
using it.
Note this doesn't fix the race internal to i915 where userspace can
trigger two VFIO_GROUP_NOTIFY_SET_KVM's before we reach a consumer of
vgpu->kvm and trigger this same UAF, it just makes the notifier
self-consistent.
Fixes:
|
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.