drbd: Fix module refcount leak in drbd_accept()

drbd_accept was modelled after kernel_accept
with drbd commit 53eb779 in July 2008.

Only, kernel_accept was then broken, and only fixed later
with kernel commit 1b08534e in Dec 2008:
net: Fix module refcount leak in kernel_accept()

Impact: protocol families provided as modules, e.g. ipv6 or ib_sdp,
would soon have their reference count become negative, preventing
them from being unloaded (likely), or worse, hit zero without actually
being unused, allowing them to be unloaded while still in use (unlikely,
but if triggered, causing a kernel crash).

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index 9b83f88c0e82ddf1cbc8ff0e8a8a2da3a0a3815f..caf3c3cd2d2ae09544c28d3e0d7f498a879a4595 100644 (file)
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -487,6 +487,7 @@ static int drbd_accept(const char **what, struct socket *sock, struct socket **n
                goto out;
        }
        (*newsock)->ops  = sock->ops;
+       __module_get((*newsock)->ops->owner);
 
 out:
        return err;