Commit 0516e42c authored by Rafael J. Wysocki's avatar Rafael J. Wysocki Committed by Greg Kroah-Hartman

ACPI: EC: Reference count query handlers under lock

[ Upstream commit 3df663a1 ]

There is a race condition in acpi_ec_get_query_handler()
theoretically allowing query handlers to go away before refernce
counting them.

In order to avoid it, call kref_get() on query handlers under
ec->mutex.

Also simplify the code a bit while at it.
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 318a2c03
......@@ -1049,29 +1049,21 @@ void acpi_ec_unblock_transactions(void)
/* --------------------------------------------------------------------------
Event Management
-------------------------------------------------------------------------- */
static struct acpi_ec_query_handler *
acpi_ec_get_query_handler(struct acpi_ec_query_handler *handler)
{
if (handler)
kref_get(&handler->kref);
return handler;
}
static struct acpi_ec_query_handler *
acpi_ec_get_query_handler_by_value(struct acpi_ec *ec, u8 value)
{
struct acpi_ec_query_handler *handler;
bool found = false;
mutex_lock(&ec->mutex);
list_for_each_entry(handler, &ec->list, node) {
if (value == handler->query_bit) {
found = true;
break;
kref_get(&handler->kref);
mutex_unlock(&ec->mutex);
return handler;
}
}
mutex_unlock(&ec->mutex);
return found ? acpi_ec_get_query_handler(handler) : NULL;
return NULL;
}
static void acpi_ec_query_handler_release(struct kref *kref)
......
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