From 5801169a2ed20003f771acecf3ac00574cf10a38 Mon Sep 17 00:00:00 2001 From: Frank Rowand Date: Tue, 18 Dec 2018 11:40:03 -0800 Subject: of: __of_detach_node() - remove node from phandle cache Non-overlay dynamic devicetree node removal may leave the node in the phandle cache. Subsequent calls to of_find_node_by_phandle() will incorrectly find the stale entry. Remove the node from the cache. Add paranoia checks in of_find_node_by_phandle() as a second level of defense (do not return cached node if detached, do not add node to cache if detached). Fixes: 0b3ce78e90fc ("of: cache phandle nodes to reduce cost of of_find_node_by_phandle()") Reported-by: Michael Bringmann Cc: stable@vger.kernel.org # v4.17+ Signed-off-by: Frank Rowand Signed-off-by: Rob Herring --- drivers/of/base.c | 31 ++++++++++++++++++++++++++++++- 1 file changed, 30 insertions(+), 1 deletion(-) (limited to 'drivers/of/base.c') diff --git a/drivers/of/base.c b/drivers/of/base.c index 4da1c688995b..5226e898476e 100644 --- a/drivers/of/base.c +++ b/drivers/of/base.c @@ -169,6 +169,28 @@ int of_free_phandle_cache(void) late_initcall_sync(of_free_phandle_cache); #endif +/* + * Caller must hold devtree_lock. + */ +void __of_free_phandle_cache_entry(phandle handle) +{ + phandle masked_handle; + struct device_node *np; + + if (!handle) + return; + + masked_handle = handle & phandle_cache_mask; + + if (phandle_cache) { + np = phandle_cache[masked_handle]; + if (np && handle == np->phandle) { + of_node_put(np); + phandle_cache[masked_handle] = NULL; + } + } +} + void of_populate_phandle_cache(void) { unsigned long flags; @@ -1214,11 +1236,18 @@ struct device_node *of_find_node_by_phandle(phandle handle) if (phandle_cache[masked_handle] && handle == phandle_cache[masked_handle]->phandle) np = phandle_cache[masked_handle]; + if (np && of_node_check_flag(np, OF_DETACHED)) { + WARN_ON(1); /* did not uncache np on node removal */ + of_node_put(np); + phandle_cache[masked_handle] = NULL; + np = NULL; + } } if (!np) { for_each_of_allnodes(np) - if (np->phandle == handle) { + if (np->phandle == handle && + !of_node_check_flag(np, OF_DETACHED)) { if (phandle_cache) { /* will put when removed from cache */ of_node_get(np); -- cgit