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authorFrank Rowand <frank.rowand@sony.com>2018-12-18 11:40:02 -0800
committerRob Herring <robh@kernel.org>2018-12-21 12:41:58 -0600
commitb8a9ac1a5b99a2fcbed19fd29d2d59270c281a31 (patch)
tree76a98444b47a29c55ba65ba95c32ac542c295431
parent24ad02c48c69c37427cc3412f6597493091eca3c (diff)
downloadlinux-b8a9ac1a5b99a2fcbed19fd29d2d59270c281a31.tar.bz2
of: of_node_get()/of_node_put() nodes held in phandle cache
The phandle cache contains struct device_node pointers. The refcount of the pointers was not incremented while in the cache, allowing use after free error after kfree() of the node. Add the proper increment and decrement of the use count. Fixes: 0b3ce78e90fc ("of: cache phandle nodes to reduce cost of of_find_node_by_phandle()") Cc: stable@vger.kernel.org # v4.17+ Signed-off-by: Frank Rowand <frank.rowand@sony.com> Signed-off-by: Rob Herring <robh@kernel.org>
-rw-r--r--drivers/of/base.c70
1 files changed, 46 insertions, 24 deletions
diff --git a/drivers/of/base.c b/drivers/of/base.c
index 998d032fcef9..4da1c688995b 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -123,9 +123,6 @@ int __weak of_node_to_nid(struct device_node *np)
}
#endif
-static struct device_node **phandle_cache;
-static u32 phandle_cache_mask;
-
/*
* Assumptions behind phandle_cache implementation:
* - phandle property values are in a contiguous range of 1..n
@@ -134,6 +131,44 @@ static u32 phandle_cache_mask;
* - the phandle lookup overhead reduction provided by the cache
* will likely be less
*/
+
+static struct device_node **phandle_cache;
+static u32 phandle_cache_mask;
+
+/*
+ * Caller must hold devtree_lock.
+ */
+static void __of_free_phandle_cache(void)
+{
+ u32 cache_entries = phandle_cache_mask + 1;
+ u32 k;
+
+ if (!phandle_cache)
+ return;
+
+ for (k = 0; k < cache_entries; k++)
+ of_node_put(phandle_cache[k]);
+
+ kfree(phandle_cache);
+ phandle_cache = NULL;
+}
+
+int of_free_phandle_cache(void)
+{
+ unsigned long flags;
+
+ raw_spin_lock_irqsave(&devtree_lock, flags);
+
+ __of_free_phandle_cache();
+
+ raw_spin_unlock_irqrestore(&devtree_lock, flags);
+
+ return 0;
+}
+#if !defined(CONFIG_MODULES)
+late_initcall_sync(of_free_phandle_cache);
+#endif
+
void of_populate_phandle_cache(void)
{
unsigned long flags;
@@ -143,8 +178,7 @@ void of_populate_phandle_cache(void)
raw_spin_lock_irqsave(&devtree_lock, flags);
- kfree(phandle_cache);
- phandle_cache = NULL;
+ __of_free_phandle_cache();
for_each_of_allnodes(np)
if (np->phandle && np->phandle != OF_PHANDLE_ILLEGAL)
@@ -162,30 +196,15 @@ void of_populate_phandle_cache(void)
goto out;
for_each_of_allnodes(np)
- if (np->phandle && np->phandle != OF_PHANDLE_ILLEGAL)
+ if (np->phandle && np->phandle != OF_PHANDLE_ILLEGAL) {
+ of_node_get(np);
phandle_cache[np->phandle & phandle_cache_mask] = np;
+ }
out:
raw_spin_unlock_irqrestore(&devtree_lock, flags);
}
-int of_free_phandle_cache(void)
-{
- unsigned long flags;
-
- raw_spin_lock_irqsave(&devtree_lock, flags);
-
- kfree(phandle_cache);
- phandle_cache = NULL;
-
- raw_spin_unlock_irqrestore(&devtree_lock, flags);
-
- return 0;
-}
-#if !defined(CONFIG_MODULES)
-late_initcall_sync(of_free_phandle_cache);
-#endif
-
void __init of_core_init(void)
{
struct device_node *np;
@@ -1200,8 +1219,11 @@ struct device_node *of_find_node_by_phandle(phandle handle)
if (!np) {
for_each_of_allnodes(np)
if (np->phandle == handle) {
- if (phandle_cache)
+ if (phandle_cache) {
+ /* will put when removed from cache */
+ of_node_get(np);
phandle_cache[masked_handle] = np;
+ }
break;
}
}