4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Christoph Hellwig hch@lst.de
[ Upstream commit 2dd4122854f697afc777582d18548dded03ce5dd ]
For kref_get_unless_zero to protect against lookup vs free races we need to use it in all places where we aren't guaranteed to already hold a reference. There is no such guarantee in nvme_find_get_ns, so switch to kref_get_unless_zero in this function.
Signed-off-by: Christoph Hellwig hch@lst.de Reviewed-by: Sagi Grimberg sagi@grimberg.me Reviewed-by: Hannes Reinecke hare@suse.com Reviewed-by: Johannes Thumshirn jthumshirn@suse.de Signed-off-by: Sasha Levin alexander.levin@verizon.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/nvme/host/core.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/drivers/nvme/host/core.c +++ b/drivers/nvme/host/core.c @@ -2299,7 +2299,8 @@ static struct nvme_ns *nvme_find_get_ns( mutex_lock(&ctrl->namespaces_mutex); list_for_each_entry(ns, &ctrl->namespaces, list) { if (ns->ns_id == nsid) { - kref_get(&ns->kref); + if (!kref_get_unless_zero(&ns->kref)) + continue; ret = ns; break; }