4.20-stable review patch. If anyone has any objections, please let me know.
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From: Frank Rowand frank.rowand@sony.com
commit 144552c786925314c1e7cb8f91a71dae1aca8798 upstream.
Add checks: - attempted kfree due to refcount reaching zero before overlay is removed - properties linked to an overlay node when the node is removed - node refcount > one during node removal in a changeset destroy, if the node was created by the changeset
After applying this patch, several validation warnings will be reported from the devicetree unittest during boot due to pre-existing devicetree bugs. The warnings will be similar to:
OF: ERROR: of_node_release(), unexpected properties in /testcase-data/overlay-node/test-bus/test-unittest11 OF: ERROR: memory leak, expected refcount 1 instead of 2, of_node_get()/of_node_put() unbalanced - destroy cset entry: attach overlay node /testcase-data-2/substation@100/ hvac-medium-2
Tested-by: Alan Tull atull@kernel.org Signed-off-by: Frank Rowand frank.rowand@sony.com Cc: Guenter Roeck linux@roeck-us.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/of/dynamic.c | 29 +++++++++++++++++++++++++++++ drivers/of/overlay.c | 1 + include/linux/of.h | 15 ++++++++++----- 3 files changed, 40 insertions(+), 5 deletions(-)
--- a/drivers/of/dynamic.c +++ b/drivers/of/dynamic.c @@ -333,6 +333,25 @@ void of_node_release(struct kobject *kob if (!of_node_check_flag(node, OF_DYNAMIC)) return;
+ if (of_node_check_flag(node, OF_OVERLAY)) { + + if (!of_node_check_flag(node, OF_OVERLAY_FREE_CSET)) { + /* premature refcount of zero, do not free memory */ + pr_err("ERROR: memory leak before free overlay changeset, %pOF\n", + node); + return; + } + + /* + * If node->properties non-empty then properties were added + * to this node either by different overlay that has not + * yet been removed, or by a non-overlay mechanism. + */ + if (node->properties) + pr_err("ERROR: %s(), unexpected properties in %pOF\n", + __func__, node); + } + property_list_free(node->properties); property_list_free(node->deadprops);
@@ -437,6 +456,16 @@ struct device_node *__of_node_dup(const
static void __of_changeset_entry_destroy(struct of_changeset_entry *ce) { + if (ce->action == OF_RECONFIG_ATTACH_NODE && + of_node_check_flag(ce->np, OF_OVERLAY)) { + if (kref_read(&ce->np->kobj.kref) > 1) { + pr_err("ERROR: memory leak, expected refcount 1 instead of %d, of_node_get()/of_node_put() unbalanced - destroy cset entry: attach overlay node %pOF\n", + kref_read(&ce->np->kobj.kref), ce->np); + } else { + of_node_set_flag(ce->np, OF_OVERLAY_FREE_CSET); + } + } + of_node_put(ce->np); list_del(&ce->node); kfree(ce); --- a/drivers/of/overlay.c +++ b/drivers/of/overlay.c @@ -373,6 +373,7 @@ static int add_changeset_node(struct ove return -ENOMEM;
tchild->parent = target_node; + of_node_set_flag(tchild, OF_OVERLAY);
ret = of_changeset_attach_node(&ovcs->cset, tchild); if (ret) --- a/include/linux/of.h +++ b/include/linux/of.h @@ -138,11 +138,16 @@ extern struct device_node *of_aliases; extern struct device_node *of_stdout; extern raw_spinlock_t devtree_lock;
-/* flag descriptions (need to be visible even when !CONFIG_OF) */ -#define OF_DYNAMIC 1 /* node and properties were allocated via kmalloc */ -#define OF_DETACHED 2 /* node has been detached from the device tree */ -#define OF_POPULATED 3 /* device already created for the node */ -#define OF_POPULATED_BUS 4 /* of_platform_populate recursed to children of this node */ +/* + * struct device_node flag descriptions + * (need to be visible even when !CONFIG_OF) + */ +#define OF_DYNAMIC 1 /* (and properties) allocated via kmalloc */ +#define OF_DETACHED 2 /* detached from the device tree */ +#define OF_POPULATED 3 /* device already created */ +#define OF_POPULATED_BUS 4 /* platform bus created for children */ +#define OF_OVERLAY 5 /* allocated for an overlay */ +#define OF_OVERLAY_FREE_CSET 6 /* in overlay cset being freed */
#define OF_BAD_ADDR ((u64)-1)