On Sun, May 17, 2015 at 08:51:01AM +0300, Haggai Eran wrote:
> @@ -212,6 +212,8 @@ struct cm_id_private {
> spinlock_t lock; /* Do not acquire inside cm.lock */
> struct completion comp;
> atomic_t refcount;
> + /* Number of clients sharing this ib_cm_id. Only valid for listeners. */
> + atomic_t sharecount;
No need for this atomic, hold the lock
The use of the atomic looks racy:
> + if (!atomic_dec_and_test(&cm_id_priv->sharecount)) {
> + /* The id is still shared. */
> + return;
> + }
Might race with this:
> + if (atomic_inc_return(&cm_id_priv->sharecount) == 1) {
> + /* This ID is already being destroyed */
> + atomic_dec(&cm_id_priv->sharecount);
> + goto new_id;
> + }
> +
Resulting in use-after-free of cm_id_priv->sharecount
Don't try and be clever with atomics, it is almost always wrong.
The share count should be 'listen_sharecount' because it *only* works
for listen.
The above test in cm_destroy_id should only be in the listen branch of
the if.
> + * Create a new listening ib_cm_id and listen on the given service ID.
> + *
> + * If there's an existing ID listening on that same device and service ID,
> + * return it.
> + *
.. Callers should call cm_destroy_id when done with the listen ..
Jason
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