IB/sa: Fix netlink local service GFP crash

Orabug: 26124118

The rdma netlink local service registers a handler to handle RESOLVE
response and another handler to handle SET_TIMEOUT request. The first
thing these handlers do is to call netlink_capable() to check the
access right of the received skb to make sure that the sender has root
access. Under normal conditions, such responses and requests will be
directly forwarded to the handlers without going through the netlink_dump
pathway (see ibnl_rcv_msg() in drivers/infiniband/core/netlink.c).
However, a user application could send a RESOLVE request (not response)
to the local service, which will fall into the netlink_dump pathway,
where a new skb will be created without initializing the control block.
This new skb will be eventually forwarded to the local service RESOLVE
response handler. Unfortunately, netlink_capable() will cause general
protection fault if the skb's control block is not initialized. This
patch will address the problem by checking the skb first.

Signed-off-by: Kaike Wan <kaike.wan@intel.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
(cherry picked from commit 2deeb4772971e56d5bdac0bd3375d5eadaa827fd)

Signed-off-by: Yuval Shaia <yuval.shaia@oracle.com>
Reviewed-by: Shamir Rabinovitch <shamir.rabinovitch@oracle.com>

diff --git a/drivers/infiniband/core/sa_query.c b/drivers/infiniband/core/sa_query.c
index 5af6c5f55184e945e0ed0837ea978e9f23428982..ced6b6d05255b265dea3e4165f5ae423bbe85ce5 100644 (file)
--- a/drivers/infiniband/core/sa_query.c
+++ b/drivers/infiniband/core/sa_query.c
@@ -715,7 +715,9 @@ static int ib_nl_handle_set_timeout(struct sk_buff *skb,
        struct nlattr *tb[LS_NLA_TYPE_MAX];
        int ret;
 
-       if (!netlink_capable(skb, CAP_NET_ADMIN))
+       if (!(nlh->nlmsg_flags & NLM_F_REQUEST) ||
+           !(NETLINK_CB(skb).sk) ||
+           !netlink_capable(skb, CAP_NET_ADMIN))
                return -EPERM;
 
        ret = nla_parse(tb, LS_NLA_TYPE_MAX - 1, nlmsg_data(nlh),
@@ -789,7 +791,9 @@ static int ib_nl_handle_resolve_resp(struct sk_buff *skb,
        int found = 0;
        int ret;
 
-       if (!netlink_capable(skb, CAP_NET_ADMIN))
+       if ((nlh->nlmsg_flags & NLM_F_REQUEST) ||
+           !(NETLINK_CB(skb).sk) ||
+           !netlink_capable(skb, CAP_NET_ADMIN))
                return -EPERM;
 
        spin_lock_irqsave(&ib_nl_request_lock, flags);