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| author |   Vivien Didelot <vivien.didelot@savoirfairelinux.com> | 2017-11-24 11:36:06 -0500 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2017-11-26 04:23:10 +0900 |
| commit | 9e741045faea17e28663f14a45f7f3304827c968 (patch) | |
| tree | 4dfbc3cad712b5fe159534f0a74259e5bc48256e /net/dsa | |
| parent | VSOCK: Don't call vsock_stream_has_data in atomic context (diff) | |
| download | linux-dev-9e741045faea17e28663f14a45f7f3304827c968.tar.xz linux-dev-9e741045faea17e28663f14a45f7f3304827c968.zip | |
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/dsa')
| -rw-r--r-- | net/dsa/dsa2.c | 25 |
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; |