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authorVivien Didelot <vivien.didelot@savoirfairelinux.com>2017-11-24 11:36:06 -0500
committerDavid S. Miller <davem@davemloft.net>2017-11-26 04:23:10 +0900
commit9e741045faea17e28663f14a45f7f3304827c968 (patch)
tree4dfbc3cad712b5fe159534f0a74259e5bc48256e /net
parentafbea2cd253b5198350dfd8edb963567d05827d6 (diff)
downloadlinux-9e741045faea17e28663f14a45f7f3304827c968.tar.bz2
net: dsa: fix 'increment on 0' warning
Setting the refcount to 0 when allocating a tree to match the number of switch devices it holds may cause an 'increment on 0; use-after-free', if CONFIG_REFCOUNT_FULL is enabled. To fix this, do not decrement the refcount of a newly allocated tree, increment it when an already allocated tree is found, and decrement it after the probing of a switch, as done with the previous behavior. At the same time, make dsa_tree_get and dsa_tree_put accept a NULL argument to simplify callers, and return the tree after incrementation, as most kref users like of_node_get and of_node_put do. Fixes: 8e5bf9759a06 ("net: dsa: simplify tree reference counting") Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Tested-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/dsa/dsa2.c25
1 files changed, 14 insertions, 11 deletions
diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c
index 44e3fb7dec8c..1e287420ff49 100644
--- a/net/dsa/dsa2.c
+++ b/net/dsa/dsa2.c
@@ -51,9 +51,7 @@ static struct dsa_switch_tree *dsa_tree_alloc(int index)
INIT_LIST_HEAD(&dst->list);
list_add_tail(&dsa_tree_list, &dst->list);
- /* Initialize the reference counter to the number of switches, not 1 */
kref_init(&dst->refcount);
- refcount_set(&dst->refcount.refcount, 0);
return dst;
}
@@ -64,20 +62,23 @@ static void dsa_tree_free(struct dsa_switch_tree *dst)
kfree(dst);
}
-static struct dsa_switch_tree *dsa_tree_touch(int index)
+static struct dsa_switch_tree *dsa_tree_get(struct dsa_switch_tree *dst)
{
- struct dsa_switch_tree *dst;
-
- dst = dsa_tree_find(index);
- if (!dst)
- dst = dsa_tree_alloc(index);
+ if (dst)
+ kref_get(&dst->refcount);
return dst;
}
-static void dsa_tree_get(struct dsa_switch_tree *dst)
+static struct dsa_switch_tree *dsa_tree_touch(int index)
{
- kref_get(&dst->refcount);
+ struct dsa_switch_tree *dst;
+
+ dst = dsa_tree_find(index);
+ if (dst)
+ return dsa_tree_get(dst);
+ else
+ return dsa_tree_alloc(index);
}
static void dsa_tree_release(struct kref *ref)
@@ -91,7 +92,8 @@ static void dsa_tree_release(struct kref *ref)
static void dsa_tree_put(struct dsa_switch_tree *dst)
{
- kref_put(&dst->refcount, dsa_tree_release);
+ if (dst)
+ kref_put(&dst->refcount, dsa_tree_release);
}
static bool dsa_port_is_dsa(struct dsa_port *port)
@@ -765,6 +767,7 @@ int dsa_register_switch(struct dsa_switch *ds)
mutex_lock(&dsa2_mutex);
err = dsa_switch_probe(ds);
+ dsa_tree_put(ds->dst);
mutex_unlock(&dsa2_mutex);
return err;