From: Colin Ian King <colin.king@xxxxxxxxxxxxx> The call to nla_nest_start_noflag can return a null pointer and currently this is not being checked and this can lead to a null pointer dereference when the null pointer dev_list is passed to function nla_nest_end. Fix this by adding in a null pointer check. Addresses-Coverity: ("Dereference null return value") Fixes: 47d902b90a32 ("nbd: add a status netlink command") Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx> --- drivers/block/nbd.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index 053958a8a2ba..ed263963e778 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -2117,6 +2117,10 @@ static int nbd_genl_status(struct sk_buff *skb, struct genl_info *info) } dev_list = nla_nest_start_noflag(reply, NBD_ATTR_DEVICE_LIST); + if (!dev_list) { + nlmsg_free(reply); + goto out; + } if (index == -1) { ret = idr_for_each(&nbd_index_idr, &status_cb, reply); if (ret) { -- 2.20.1