diff options
| author | Frank Rowand <frank.rowand@sony.com> | 2018-12-18 22:40:03 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-01-13 11:51:10 +0300 |
| commit | 8dbea64423dca8a357aeea7160713ba9c0e26845 (patch) | |
| tree | 68d1500ec493c343579fa4f2bfb0bf1683030071 /drivers/of | |
| parent | 1cb5a0333a5d2b3e79c318751d71a080a7869a88 (diff) | |
| download | linux-8dbea64423dca8a357aeea7160713ba9c0e26845.tar.xz | |
of: __of_detach_node() - remove node from phandle cache
commit 5801169a2ed20003f771acecf3ac00574cf10a38 upstream.
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 <mwb@linux.vnet.ibm.com>
Cc: stable@vger.kernel.org # v4.17+
Signed-off-by: Frank Rowand <frank.rowand@sony.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/of')
| -rw-r--r-- | drivers/of/base.c | 31 | ||||
| -rw-r--r-- | drivers/of/dynamic.c | 3 | ||||
| -rw-r--r-- | drivers/of/of_private.h | 4 |
3 files changed, 37 insertions, 1 deletions
diff --git a/drivers/of/base.c b/drivers/of/base.c index 0470cbbed560..3f21ea6a90dc 100644 --- a/drivers/of/base.c +++ b/drivers/of/base.c @@ -161,6 +161,28 @@ 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; @@ -1169,11 +1191,18 @@ 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); diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c index f4f8ed9b5454..ecea92f68c87 100644 --- a/drivers/of/dynamic.c +++ b/drivers/of/dynamic.c @@ -268,6 +268,9 @@ void __of_detach_node(struct device_node *np) } of_node_set_flag(np, OF_DETACHED); + + /* race with of_find_node_by_phandle() prevented by devtree_lock */ + __of_free_phandle_cache_entry(np->phandle); } /** diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h index 216175d11d3d..f5da842841e5 100644 --- a/drivers/of/of_private.h +++ b/drivers/of/of_private.h @@ -76,6 +76,10 @@ static inline void __of_detach_node_sysfs(struct device_node *np) {} int of_resolve_phandles(struct device_node *tree); #endif +#if defined(CONFIG_OF_DYNAMIC) +void __of_free_phandle_cache_entry(phandle handle); +#endif + #if defined(CONFIG_OF_OVERLAY) void of_overlay_mutex_lock(void); void of_overlay_mutex_unlock(void); |