pnv_npu2_init_context wasn't checking the return code from
__mmu_notifier_register. If __mmu_notifier_register failed, the
npu_context was still assigned to the mm and the caller wasn't given any
indication that things went wrong. Later on pnv_npu2_destroy_context would
be called, which in turn called mmu_notifier_unregister and dropped
mm->mm_count without having incremented it in the first place. This led to
various forms of corruption like mm use-after-free and mm double-free.
__mmu_notifier_register can fail with EINTR if a signal is pending, so
this case can be frequent.
This patch calls opal_npu_destroy_context on the failure paths, and makes
sure not to assign mm->context.npu_context until past the failure points.
Signed-off-by: Mark Hairgrove <mhairgr...@nvidia.com>
---
arch/powerpc/platforms/powernv/npu-dma.c | 32 +++++++++++++++++++----------
1 files changed, 21 insertions(+), 11 deletions(-)
diff --git a/arch/powerpc/platforms/powernv/npu-dma.c
b/arch/powerpc/platforms/powernv/npu-dma.c
index f6cbc1a..48c73aa 100644
--- a/arch/powerpc/platforms/powernv/npu-dma.c
+++ b/arch/powerpc/platforms/powernv/npu-dma.c
@@ -677,6 +677,11 @@ struct npu_context *pnv_npu2_init_context(struct pci_dev
*gpdev,
/* No nvlink associated with this GPU device */
return ERR_PTR(-ENODEV);
+ nvlink_dn = of_parse_phandle(npdev->dev.of_node, "ibm,nvlink", 0);
+ if (WARN_ON(of_property_read_u32(nvlink_dn, "ibm,npu-link-index",
+ &nvlink_index)))
+ return ERR_PTR(-ENODEV);
+
if (!mm || mm->context.id == 0) {
/*
* Kernel thread contexts are not supported and context id 0 is
@@ -704,25 +709,30 @@ struct npu_context *pnv_npu2_init_context(struct pci_dev
*gpdev,
*/
npu_context = mm->context.npu_context;
if (!npu_context) {
+ rc = -ENOMEM;
npu_context = kzalloc(sizeof(struct npu_context), GFP_KERNEL);
- if (!npu_context)
- return ERR_PTR(-ENOMEM);
+ if (npu_context) {
+ kref_init(&npu_context->kref);
+ npu_context->mm = mm;
+ npu_context->mn.ops = &nv_nmmu_notifier_ops;
+ rc = __mmu_notifier_register(&npu_context->mn, mm);
+ }
+
+ if (rc) {
+ kfree(npu_context);
+ opal_npu_destroy_context(nphb->opal_id, mm->context.id,
+ PCI_DEVID(gpdev->bus->number,
+ gpdev->devfn));
+ return ERR_PTR(rc);
+ }
mm->context.npu_context = npu_context;
- npu_context->mm = mm;
- npu_context->mn.ops = &nv_nmmu_notifier_ops;
- __mmu_notifier_register(&npu_context->mn, mm);
- kref_init(&npu_context->kref);
} else {
- kref_get(&npu_context->kref);
+ WARN_ON(!kref_get_unless_zero(&npu_context->kref));
}
npu_context->release_cb = cb;
npu_context->priv = priv;
- nvlink_dn = of_parse_phandle(npdev->dev.of_node, "ibm,nvlink", 0);
- if (WARN_ON(of_property_read_u32(nvlink_dn, "ibm,npu-link-index",
- &nvlink_index)))
- return ERR_PTR(-ENODEV);
npu_context->npdev[npu->index][nvlink_index] = npdev;
if (!nphb->npu.nmmu_flush) {
--
1.7.2.5
