genetlink: pin family module during policy dump

The generic netlink controller's policy dump keeps pointers to the target
family's operation and policy tables in its callback state.  A dump may be
split across multiple skbs and remain pending after the initial request.

Netlink pins the module which owns the dump callback, but in this case
that is the controller's owner rather than the target family's owner.  The
target family can consequently be unregistered and its module unloaded
while a policy dump is pending.  Advancing the dump then dereferences
policy memory from the unloaded module.

Take a reference to the target family's module when the dump starts.
Drop it from the error and done paths.  This matches the lifetime for which
the dump context retains the family and policy pointers.

Fixes: d07dcf9aadd6 ("netlink: add infrastructure to expose policies to userspace")
Cc: stable@vger.kernel.org
Signed-off-by: XingWang Xiang <v3rdant.xiang@gmail.com>
Link: https://patch.msgid.link/20260902084317.4092542-1-v3rdant.xiang@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

0 files changed, 0 insertions, 0 deletions