netfilter: nf_tables: fix potential NULL-ptr deref in nf_tables_dump_obj_done()

If there is no NFTA_OBJ_TABLE and NFTA_OBJ_TYPE, the c.data will be NULL in
nf_tables_getobj(). So before free filter->table in nf_tables_dump_obj_done(),
we need to check if filter is NULL first.

Fixes: e46abbcc05aa ("netfilter: nf_tables: Allow table names of up to 255 chars")
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Acked-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 4 insertions, 2 deletions

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 8d4526651661..07bd4138c84e 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -4665,8 +4665,10 @@ static int nf_tables_dump_obj_done(struct netlink_callback *cb)
 {
         struct nft_obj_filter *filter = cb->data;
 
-        kfree(filter->table);
-        kfree(filter);
+        if (filter) {
+                kfree(filter->table);
+                kfree(filter);
+        }
 
         return 0;
 }