gtp: fix wrong condition in gtp_genl_dump_pdp()

BugLink: https://bugs.launchpad.net/bugs/1860816
[ Upstream commit 94a6d9fb88df43f92d943c32b84ce398d50bf49f ]

gtp_genl_dump_pdp() is ->dumpit() callback of GTP module and it is used
to dump pdp contexts. it would be re-executed because of dump packet size.

If dump packet size is too big, it saves current dump pointer
(gtp interface pointer, bucket, TID value) then it restarts dump from
last pointer.
Current GTP code allows adding zero TID pdp context but dump code
ignores zero TID value. So, last dump pointer will not be found.

In addition, this patch adds missing rcu_read_lock() in
gtp_genl_dump_pdp().

Fixes: 459aa660eb1d ("gtp: add initial driver for datapath of GPRS Tunneling Protocol (GTP-U)")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c
index 1f754e30baf2eeea8c58c6ac36e5bfa2db3e668a..a0595b67ad47e32bf55d8f28d3eb6e8b8d2b69a1 100644 (file)
--- a/drivers/net/gtp.c
+++ b/drivers/net/gtp.c
@@ -38,7 +38,6 @@ struct pdp_ctx {
        struct hlist_node       hlist_addr;
 
        union {
-               u64             tid;
                struct {
                        u64     tid;
                        u16     flow;
@@ -1244,43 +1243,46 @@ static int gtp_genl_dump_pdp(struct sk_buff *skb,
                                struct netlink_callback *cb)
 {
        struct gtp_dev *last_gtp = (struct gtp_dev *)cb->args[2], *gtp;
+       int i, j, bucket = cb->args[0], skip = cb->args[1];
        struct net *net = sock_net(skb->sk);
-       struct gtp_net *gn = net_generic(net, gtp_net_id);
-       unsigned long tid = cb->args[1];
-       int i, k = cb->args[0], ret;
        struct pdp_ctx *pctx;
+       struct gtp_net *gn;
+
+       gn = net_generic(net, gtp_net_id);
 
        if (cb->args[4])
                return 0;
 
+       rcu_read_lock();
        list_for_each_entry_rcu(gtp, &gn->gtp_dev_list, list) {
                if (last_gtp && last_gtp != gtp)
                        continue;
                else
                        last_gtp = NULL;
 
-               for (i = k; i < gtp->hash_size; i++) {
-                       hlist_for_each_entry_rcu(pctx, &gtp->tid_hash[i], hlist_tid) {
-                               if (tid && tid != pctx->u.tid)
-                                       continue;
-                               else
-                                       tid = 0;
-
-                               ret = gtp_genl_fill_info(skb,
-                                                        NETLINK_CB(cb->skb).portid,
-                                                        cb->nlh->nlmsg_seq,
-                                                        cb->nlh->nlmsg_type, pctx);
-                               if (ret < 0) {
+               for (i = bucket; i < gtp->hash_size; i++) {
+                       j = 0;
+                       hlist_for_each_entry_rcu(pctx, &gtp->tid_hash[i],
+                                                hlist_tid) {
+                               if (j >= skip &&
+                                   gtp_genl_fill_info(skb,
+                                           NETLINK_CB(cb->skb).portid,
+                                           cb->nlh->nlmsg_seq,
+                                           cb->nlh->nlmsg_type, pctx)) {
                                        cb->args[0] = i;
-                                       cb->args[1] = pctx->u.tid;
+                                       cb->args[1] = j;
                                        cb->args[2] = (unsigned long)gtp;
                                        goto out;
                                }
+                               j++;
                        }
+                       skip = 0;
                }
+               bucket = 0;
        }
        cb->args[4] = 1;
 out:
+       rcu_read_unlock();
        return skb->len;
 }