Robin Murphy
2020-Jul-01 10:53 UTC
[PATCH v3 00/34] iommu: Move iommu_group setup to IOMMU core code
On 2020-07-01 01:40, Qian Cai wrote:> Looks like this patchset introduced an use-after-free on arm-smmu-v3. > > Reproduced using mlx5, > > # echo 1 > /sys/class/net/enp11s0f1np1/device/sriov_numvfs > # echo 0 > /sys/class/net/enp11s0f1np1/device/sriov_numvfs > > The .config, > https://github.com/cailca/linux-mm/blob/master/arm64.config > > Looking at the free stack, > > iommu_release_device->iommu_group_remove_device > > was introduced in 07/34 ("iommu: Add probe_device() and release_device() > call-backs").Right, iommu_group_remove_device can tear down the group and call ->domain_free before the driver has any knowledge of the last device going away via the ->release_device call. I guess the question is do we simply flip the call order in iommu_release_device() so drivers can easily clean up their internal per-device state first, or do we now want them to be robust against freeing domains with devices still nominally attached? Robin.