[PATCH v2] RDMA/core: Clear driver_udata before destroying objects in rdma_core

[Jacob Moroni <jmoroni@google.com>]

When uobject creation fails while copying user output data (i.e.,
after the HW object has been created), it calls
rdma_alloc_abort_uobject() with hw_obj_valid=true which then
invokes the object's destroy callback, but passes the
uverbs_attr_bundle from the original creation command.

The issue is that drivers are expected to validate the udata
and return an error if there's unexpected content, and data from
the wrong command counts as "unexpected content", so this ends
up causing the driver's destroy call to fail.

A similar issue exists in the rereg_mr path when a new MR
is created and the old one is destroyed.

Fix this by clearing driver_udata before invoking the driver's
destroy method.

Fixes: 6e0954b11c05 ("RDMA/uverbs: Allow drivers to create a new HW object during rereg_mr")
Fixes: 0ac8903cbbe6 ("RDMA/core: Allow the ioctl layer to abort a fully created uobject")
Signed-off-by: Jacob Moroni <jmoroni@google.com>
---
Changes in v2:
- Drop redundant NULL check in create_qp() now that
  uverbs_get_cleared_udata() handles NULL (Leon)

 drivers/infiniband/core/ib_core_uverbs.c | 12 ------------
 drivers/infiniband/core/rdma_core.c      |  2 ++
 drivers/infiniband/core/rdma_core.h      | 17 +++++++++++------
 drivers/infiniband/core/verbs.c          |  3 +--
 4 files changed, 14 insertions(+), 20 deletions(-)

diff --git a/drivers/infiniband/core/ib_core_uverbs.c b/drivers/infiniband/core/ib_core_uverbs.c
index 41c84ffe8c09..1482d9b27b38 100644
--- a/drivers/infiniband/core/ib_core_uverbs.c
+++ b/drivers/infiniband/core/ib_core_uverbs.c
@@ -535,18 +535,6 @@ int uverbs_destroy_def_handler(struct uverbs_attr_bundle *attrs)
 }
 EXPORT_SYMBOL(uverbs_destroy_def_handler);
 
-/*
- * When calling a destroy function during an error unwind we need to pass in
- * the udata that is sanitized of all user arguments. Ie from the driver
- * perspective it looks like no udata was passed.
- */
-struct ib_udata *uverbs_get_cleared_udata(struct uverbs_attr_bundle *attrs)
-{
-	attrs->driver_udata = (struct ib_udata){};
-	return &attrs->driver_udata;
-}
-EXPORT_SYMBOL_NS_GPL(uverbs_get_cleared_udata, "rdma_core");
-
 /**
  * _uverbs_alloc() - Quickly allocate memory for use with a bundle
  * @bundle: The bundle
diff --git a/drivers/infiniband/core/rdma_core.c b/drivers/infiniband/core/rdma_core.c
index a7cbe643e33c..b32e5445601b 100644
--- a/drivers/infiniband/core/rdma_core.c
+++ b/drivers/infiniband/core/rdma_core.c
@@ -734,6 +734,7 @@ void rdma_assign_uobject(struct ib_uobject *to_uobj, struct ib_uobject *new_uobj
 	 * If this fails then the uobject is still completely valid (though with
 	 * a new ID) and we leak it until context close.
 	 */
+	uverbs_get_cleared_udata(attrs);
 	uverbs_destroy_uobject(to_uobj, RDMA_REMOVE_DESTROY, attrs);
 }
 EXPORT_SYMBOL_NS_GPL(rdma_assign_uobject, "rdma_core");
@@ -750,6 +751,7 @@ void rdma_alloc_abort_uobject(struct ib_uobject *uobj,
 	int ret;
 
 	if (hw_obj_valid) {
+		uverbs_get_cleared_udata(attrs);
 		ret = uobj->uapi_object->type_class->destroy_hw(
 			uobj, RDMA_REMOVE_ABORT, attrs);
 		/*
diff --git a/drivers/infiniband/core/rdma_core.h b/drivers/infiniband/core/rdma_core.h
index 2b91e8527287..9de14e625dd3 100644
--- a/drivers/infiniband/core/rdma_core.h
+++ b/drivers/infiniband/core/rdma_core.h
@@ -71,14 +71,19 @@ int uverbs_output_written(const struct uverbs_attr_bundle *bundle, size_t idx);
 
 void setup_ufile_idr_uobject(struct ib_uverbs_file *ufile);
 
-#if IS_ENABLED(CONFIG_INFINIBAND_USER_ACCESS)
-struct ib_udata *uverbs_get_cleared_udata(struct uverbs_attr_bundle *attrs);
-#else
-static inline struct ib_udata *uverbs_get_cleared_udata(struct uverbs_attr_bundle *attrs)
+/*
+ * When calling a destroy function during an error unwind we need to pass in
+ * the udata that is sanitized of all user arguments. Ie from the driver
+ * perspective it looks like no udata was passed.
+ */
+static inline struct ib_udata *
+uverbs_get_cleared_udata(struct uverbs_attr_bundle *attrs)
 {
-	return NULL;
+	if (!attrs)
+		return NULL;
+	attrs->driver_udata = (struct ib_udata){};
+	return &attrs->driver_udata;
 }
-#endif
 
 /*
  * This is the runtime description of the uverbs API, used by the syscall
diff --git a/drivers/infiniband/core/verbs.c b/drivers/infiniband/core/verbs.c
index 6d5825114c19..edf62652f9d3 100644
--- a/drivers/infiniband/core/verbs.c
+++ b/drivers/infiniband/core/verbs.c
@@ -1331,8 +1331,7 @@ static struct ib_qp *create_qp(struct ib_device *dev, struct ib_pd *pd,
 	return qp;
 
 err_security:
-	qp->device->ops.destroy_qp(
-		qp, uattrs ? uverbs_get_cleared_udata(uattrs) : NULL);
+	qp->device->ops.destroy_qp(qp, uverbs_get_cleared_udata(uattrs));
 err_create:
 	rdma_restrack_put(&qp->res);
 	xa_destroy(&qp->comp_cntrs);
-- 
2.56.0.rc1.315.gc6ed9934b7-goog