From d21e540b4dd74a26df7a66ebab75c693a4a6a861 Mon Sep 17 00:00:00 2001 From: Liping Zhang Date: Sat, 7 Jan 2017 20:51:50 +0800 Subject: [PATCH] netfilter: nf_tables: fix possible oops when dumping stateful objects When dumping nft stateful objects, if NFTA_OBJ_TABLE and NFTA_OBJ_TYPE attributes are not specified either, filter will become NULL, so oops will happen(actually nft utility will always set NFTA_OBJ_TABLE attr, so I write a test program to make this happen): BUG: unable to handle kernel NULL pointer dereference at (null) IP: nf_tables_dump_obj+0x17c/0x330 [nf_tables] [...] Call Trace: ? nf_tables_dump_obj+0x5/0x330 [nf_tables] ? __kmalloc_reserve.isra.35+0x31/0x90 ? __alloc_skb+0x5b/0x1e0 netlink_dump+0x124/0x2a0 __netlink_dump_start+0x161/0x190 nf_tables_getobj+0xe8/0x280 [nf_tables] Fixes: a9fea2a3c3cf ("netfilter: nf_tables: allow to filter stateful object dumps by type") Signed-off-by: Liping Zhang Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_tables_api.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 0db5f9782265..091d2dcc63b2 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -4262,10 +4262,11 @@ static int nf_tables_dump_obj(struct sk_buff *skb, struct netlink_callback *cb) if (idx > s_idx) memset(&cb->args[1], 0, sizeof(cb->args) - sizeof(cb->args[0])); - if (filter->table[0] && + if (filter && filter->table[0] && strcmp(filter->table, table->name)) goto cont; - if (filter->type != NFT_OBJECT_UNSPEC && + if (filter && + filter->type != NFT_OBJECT_UNSPEC && obj->type->type != filter->type) goto cont; -- 2.30.2