6.16-stable review patch. If anyone has any objections, please let me know.
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From: Jason Gunthorpe jgg@nvidia.com
[ Upstream commit 53d0584eeb2c85a46c83656246d61a89558d74b3 ]
If something holds a refcount then it is at risk of UAFing. For abort paths we expect the caller to never share the object with a parallel thread and to clean up any refcounts it obtained on its own.
Add the missing dec inside iommufd_hwpt_paging_alloc() during error unwind by making iommufd_hw_pagetable_attach/detach() proper pairs.
Link: https://patch.msgid.link/r/2-v1-02cd136829df+31-iommufd_syz_fput_jgg@nvidia.... Reviewed-by: Kevin Tian kevin.tian@intel.com Reviewed-by: Nicolin Chen nicolinc@nvidia.com Tested-by: Nicolin Chen nicolinc@nvidia.com Signed-off-by: Jason Gunthorpe jgg@nvidia.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/iommu/iommufd/device.c | 3 ++- drivers/iommu/iommufd/iommufd_private.h | 3 +-- drivers/iommu/iommufd/main.c | 4 ++++ 3 files changed, 7 insertions(+), 3 deletions(-)
diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c index 86244403b5320..674f9f244f7b4 100644 --- a/drivers/iommu/iommufd/device.c +++ b/drivers/iommu/iommufd/device.c @@ -661,6 +661,8 @@ iommufd_hw_pagetable_detach(struct iommufd_device *idev, ioasid_t pasid) iopt_remove_reserved_iova(&hwpt_paging->ioas->iopt, idev->dev); mutex_unlock(&igroup->lock);
+ iommufd_hw_pagetable_put(idev->ictx, hwpt); + /* Caller must destroy hwpt */ return hwpt; } @@ -1007,7 +1009,6 @@ void iommufd_device_detach(struct iommufd_device *idev, ioasid_t pasid) hwpt = iommufd_hw_pagetable_detach(idev, pasid); if (!hwpt) return; - iommufd_hw_pagetable_put(idev->ictx, hwpt); refcount_dec(&idev->obj.users); } EXPORT_SYMBOL_NS_GPL(iommufd_device_detach, "IOMMUFD"); diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h index 9ccc83341f321..e68d8d63076a8 100644 --- a/drivers/iommu/iommufd/iommufd_private.h +++ b/drivers/iommu/iommufd/iommufd_private.h @@ -390,9 +390,8 @@ static inline void iommufd_hw_pagetable_put(struct iommufd_ctx *ictx, if (hwpt->obj.type == IOMMUFD_OBJ_HWPT_PAGING) { struct iommufd_hwpt_paging *hwpt_paging = to_hwpt_paging(hwpt);
- lockdep_assert_not_held(&hwpt_paging->ioas->mutex); - if (hwpt_paging->auto_domain) { + lockdep_assert_not_held(&hwpt_paging->ioas->mutex); iommufd_object_put_and_try_destroy(ictx, &hwpt->obj); return; } diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c index 62a3469bbd37e..2b26747ac2021 100644 --- a/drivers/iommu/iommufd/main.c +++ b/drivers/iommu/iommufd/main.c @@ -62,6 +62,10 @@ void iommufd_object_abort(struct iommufd_ctx *ictx, struct iommufd_object *obj) old = xas_store(&xas, NULL); xa_unlock(&ictx->objects); WARN_ON(old != XA_ZERO_ENTRY); + + if (WARN_ON(!refcount_dec_and_test(&obj->users))) + return; + kfree(obj); }