netdev - [PATCH net 3/5] netfilter: nft_flow_offload: release dst in case direct xmit path is used

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Message-Id: <20240222000843.146665-4-pablo@netfilter.org>
Date: Thu, 22 Feb 2024 01:08:41 +0100
From: Pablo Neira Ayuso <pablo@...filter.org>
To: netfilter-devel@...r.kernel.org
Cc: davem@...emloft.net,
	netdev@...r.kernel.org,
	kuba@...nel.org,
	pabeni@...hat.com,
	edumazet@...gle.com,
	fw@...len.de
Subject: [PATCH net 3/5] netfilter: nft_flow_offload: release dst in case direct xmit path is used

Direct xmit does not use it since it calls dev_queue_xmit() to send
packets, hence it calls dst_release().

kmemleak reports:

unreferenced object 0xffff88814f440900 (size 184):
  comm "softirq", pid 0, jiffies 4294951896
  hex dump (first 32 bytes):
    00 60 5b 04 81 88 ff ff 00 e6 e8 82 ff ff ff ff  .`[.............
    21 0b 50 82 ff ff ff ff 00 00 00 00 00 00 00 00  !.P.............
  backtrace (crc cb2bf5d6):
    [<000000003ee17107>] kmem_cache_alloc+0x286/0x340
    [<0000000021a5de2c>] dst_alloc+0x43/0xb0
    [<00000000f0671159>] rt_dst_alloc+0x2e/0x190
    [<00000000fe5092c9>] __mkroute_output+0x244/0x980
    [<000000005fb96fb0>] ip_route_output_flow+0xc0/0x160
    [<0000000045367433>] nf_ip_route+0xf/0x30
    [<0000000085da1d8e>] nf_route+0x2d/0x60
    [<00000000d1ecd1cb>] nft_flow_route+0x171/0x6a0 [nft_flow_offload]
    [<00000000d9b2fb60>] nft_flow_offload_eval+0x4e8/0x700 [nft_flow_offload]
    [<000000009f447dbb>] expr_call_ops_eval+0x53/0x330 [nf_tables]
    [<00000000072e1be6>] nft_do_chain+0x17c/0x840 [nf_tables]
    [<00000000d0551029>] nft_do_chain_inet+0xa1/0x210 [nf_tables]
    [<0000000097c9d5c6>] nf_hook_slow+0x5b/0x160
    [<0000000005eccab1>] ip_forward+0x8b6/0x9b0
    [<00000000553a269b>] ip_rcv+0x221/0x230
    [<00000000412872e5>] __netif_receive_skb_one_core+0xfe/0x110

Fixes: fa502c865666 ("netfilter: flowtable: simplify route logic")
Reported-by: Florian Westphal <fw@...len.de>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
 net/netfilter/nf_flow_table_core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/netfilter/nf_flow_table_core.c b/net/netfilter/nf_flow_table_core.c
index 7502d6d73a60..a0571339239c 100644
--- a/net/netfilter/nf_flow_table_core.c
+++ b/net/netfilter/nf_flow_table_core.c
@@ -132,6 +132,7 @@ static int flow_offload_fill_route(struct flow_offload *flow,
 		       ETH_ALEN);
 		flow_tuple->out.ifidx = route->tuple[dir].out.ifindex;
 		flow_tuple->out.hw_ifidx = route->tuple[dir].out.hw_ifindex;
+		dst_release(dst);
 		break;
 	case FLOW_OFFLOAD_XMIT_XFRM:
 	case FLOW_OFFLOAD_XMIT_NEIGH:
-- 
2.30.2