[PATCH rdma-next 6/8] RDMA/netlink: Protect device query from device removal

Leon Romanovsky
2017-12-24T13:43:26Z

There is a chance that device will be removed during device query
operations and it will cause to kernel panic in the flows which
doesn't hold lists_rwsem semaphore.

Fixes: e5c9469efcb1 ("RDMA/netlink: Add nldev device doit implementation")
Reviewed-by: Mark Bloch <markb-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
Signed-off-by: Leon Romanovsky <leonro-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
---
drivers/infiniband/core/nldev.c | 25 +++++++++++++++----------
1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/drivers/infiniband/core/nldev.c b/drivers/infiniband/core/nldev.c
index 2b631307349d..e3033d7a4029 100644
--- a/drivers/infiniband/core/nldev.c
+++ b/drivers/infiniband/core/nldev.c
@@ -141,36 +141,41 @@ static int nldev_get_doit(struct sk_buff *skb, struct nlmsghdr *nlh,
struct ib_device *device;
struct sk_buff *msg;
u32 index;
- int err;
+ int ret = -ENOMEM;

- err = nlmsg_parse(nlh, 0, tb, RDMA_NLDEV_ATTR_MAX - 1,
+ ret = nlmsg_parse(nlh, 0, tb, RDMA_NLDEV_ATTR_MAX - 1,
nldev_policy, extack);
- if (err || !tb[RDMA_NLDEV_ATTR_DEV_INDEX])
+ if (ret || !tb[RDMA_NLDEV_ATTR_DEV_INDEX])
return -EINVAL;

index = nla_get_u32(tb[RDMA_NLDEV_ATTR_DEV_INDEX]);

- device = __ib_device_get_by_index(index);
+ device = ib_device_get_by_index(index);
if (!device)
return -EINVAL;

msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
if (!msg)
- return -ENOMEM;
+ goto err;

nlh = nlmsg_put(msg, NETLINK_CB(skb).portid, nlh->nlmsg_seq,
RDMA_NL_GET_TYPE(RDMA_NL_NLDEV, RDMA_NLDEV_CMD_GET),
0, 0);

- err = fill_dev_info(msg, device);
- if (err) {
- nlmsg_free(msg);
- return err;
- }
+ ret = fill_dev_info(msg, device);
+ if (ret)
+ goto err_free;

nlmsg_end(msg, nlh);

+ put_device(&device->dev);
return rdma_nl_unicast(msg, NETLINK_CB(skb).portid);
+
+err_free:
+ nlmsg_free(msg);
+err:
+ put_device(&device->dev);
+ return ret;
}

static int _nldev_get_dumpit(struct ib_device *device,