netdev - Re: [PATCH v3 net 1/2] dccp/tcp: Avoid negative sk_forward_alloc by ipv6

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Date:   Mon, 27 Feb 2023 01:17:55 +0100
From:   Hauke Mehrtens <hauke@...ke-m.de>
To:     Kuniyuki Iwashima <kuniyu@...zon.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>
Cc:     Kuniyuki Iwashima <kuni1840@...il.com>, netdev@...r.kernel.org,
        Andrii <tulup@...l.ru>,
        Arnaldo Carvalho de Melo <acme@...driva.com>,
        Shiji Yang <yangshiji66@...com>
Subject: Re: [PATCH v3 net 1/2] dccp/tcp: Avoid negative sk_forward_alloc by
 ipv6_pinfo.pktoptions.

On 2/10/23 01:22, Kuniyuki Iwashima wrote:
> Eric Dumazet pointed out [0] that when we call skb_set_owner_r()
> for ipv6_pinfo.pktoptions, sk_rmem_schedule() has not been called,
> resulting in a negative sk_forward_alloc.
> 
> We add a new helper which clones a skb and sets its owner only
> when sk_rmem_schedule() succeeds.
> 
> Note that we move skb_set_owner_r() forward in (dccp|tcp)_v6_do_rcv()
> because tcp_send_synack() can make sk_forward_alloc negative before
> ipv6_opt_accepted() in the crossed SYN-ACK or self-connect() cases.
> 
> [0]: https://lore.kernel.org/netdev/CANn89iK9oc20Jdi_41jb9URdF210r7d1Y-+uypbMSbOfY6jqrg@mail.gmail.com/
> 
> Fixes: 323fbd0edf3f ("net: dccp: Add handling of IPV6_PKTOPTIONS to dccp_v6_do_rcv()")
> Fixes: 3df80d9320bc ("[DCCP]: Introduce DCCPv6")
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.com>
> ---
> Cc: Andrii <tulup@...l.ru>
> Cc: Arnaldo Carvalho de Melo <acme@...driva.com>
> ---
>   include/net/sock.h  | 13 +++++++++++++
>   net/dccp/ipv6.c     |  7 ++-----
>   net/ipv6/tcp_ipv6.c | 10 +++-------
>   3 files changed, 18 insertions(+), 12 deletions(-)
> 
Hi,

Multiples people reported kernel warnings after the upgrade from kernel 
5.15.94 to 5.15.95 in OpenWrt master, see 
https://github.com/openwrt/openwrt/pull/12071

This was seen on a MIPS and a x86 CPU. It is happening when a Windows 
client connected, it works fine when an Android or iPad connects.

OpenWrt has some additional patches on top of the kernel, we haven't 
checked yet if they are causing this problem in combination with this 
new change. With kernel 5.15.94 as a base it works fine.

The problem is not showing up when the backport of this patch is reverted.

This warning was reported:

[  257.978586] ------------[ cut here ]------------
[  257.987882] WARNING: CPU: 0 PID: 4377 at net/core/stream.c:212 
inet_csk_destroy_sock+0x6c/0x17c
[  258.005287] Modules linked in: rt2800soc rt2800mmio rt2800lib pppoe 
ppp_async nft_fib_inet nf_flow_table_ipv6 nf_flow_table_ipv4 
nf_flow_table_inet rt2x00soc rt2x00mmio rt2x00lib pppox ppp_generic 
nft_reject_ipv6 nft_reject_ipv4 nft_reject_inet nft_reject nft_redir 
nft_quota nft_objref nft_numgen nft_nat nft_masq nft_log nft_limit 
nft_hash nft_flow_offload nft_fib_ipv6 nft_fib_ipv4 nft_fib nft_ct 
nft_counter nft_chain_nat nf_tables nf_nat nf_flow_table nf_conntrack 
mt76x2e mt76x2_common mt76x02_lib mt76 mac80211 lzo cfg80211 slhc 
nfnetlink nf_reject_ipv6 nf_reject_ipv4 nf_log_syslog nf_defrag_ipv6 
nf_defrag_ipv4 lzo_rle lzo_decompress lzo_compress libcrc32c crc_ccitt 
compat sha256_generic libsha256 seqiv jitterentropy_rng drbg hmac cmac 
crypto_acompress leds_gpio gpio_button_hotplug crc32c_generic
[  258.146540] CPU: 0 PID: 4377 Comm: dnsmasq Tainted: G        W 
  5.15.95 #0
[  258.161475] Stack : 00000000 00000000 80c099dc 80860000 806b0000 
80608730 80f19830 806abe23
[  258.178178]         808633b4 00001119 00000003 80061c60 80601eac 
00000001 80c09998 84245f1d
[  258.194872]         00000000 00000000 80608730 80c09830 fffff171 
00000000 00000000 ffffffea
[  258.211568]         00000000 80c0983c 00000171 806b2278 80860000 
00000009 00000000 804651e0
[  258.228273]         00000009 00000003 00000002 00000006 00000018 
803347a4 00000000 80860000
[  258.244993]         ...
[  258.249877] Call Trace:
[  258.254737] [<8000700c>] show_stack+0x28/0xf0
[  258.263459] [<8002622c>] __warn+0x9c/0x124
[  258.271649] [<80026310>] warn_slowpath_fmt+0x5c/0xac
[  258.281564] [<804651e0>] inet_csk_destroy_sock+0x6c/0x17c
[  258.292356] [<80479328>] tcp_reset+0x50/0xb0
[  258.300896] [<8047973c>] tcp_validate_incoming+0x3b4/0x624
[  258.311853] [<8047bc48>] tcp_rcv_state_process+0x32c/0xf80
[  258.322810] [<80521fa0>] tcp_v6_do_rcv+0x290/0x4e4
[  258.332400] [<80522da0>] tcp_v6_rcv+0xbac/0xc3c
[  258.341454] [<804e6798>] ip6_protocol_deliver_rcu+0x118/0x640
[  258.352945] [<804e6d6c>] ip6_input+0x84/0x9c
[  258.361477] [<803e224c>] __netif_receive_skb_one_core+0x44/0x54
[  258.373306] [<803e22ac>] netif_receive_skb+0x34/0xc8
[  258.383221] [<8054ba34>] br_handle_frame_finish+0x330/0x5b0
[  258.394362] [<8054c140>] br_handle_frame+0x48c/0x4fc
[  258.404279] [<803dfa30>] __netif_receive_skb_core.constprop.0+0x268/0xc30
[  258.417839] [<803e04e4>] __netif_receive_skb_list_core+0xec/0x224
[  258.430008] [<803e07c0>] netif_receive_skb_list_internal+0x1a4/0x254
[  258.442718] [<81c35b08>] ieee80211_rx_napi+0x84/0x8c [mac80211]
[  258.454881] [<819e07c0>] rt2x00lib_rxdone+0x318/0x940 [rt2x00lib]
[  258.467100] [<819bf08c>] rt2x00mmio_rxdone+0x8c/0xd8 [rt2x00mmio]
[  258.479279] [<819f6df0>] rt2800mmio_rxdone_tasklet+0x18/0xac [rt2800mmio]
[  258.492844] [<800294ec>] tasklet_action_common.constprop.0+0xc0/0xf8
[  258.505545] [<8057742c>] __do_softirq+0x10c/0x2c4
[  258.514934] [<80002950>] except_vec_vi_end+0xb8/0xc4
[  258.524847] [<8013b058>] __do_munmap+0xac/0x54c
[  258.533917] [<8013b55c>] __vm_munmap+0x64/0xd4
[  258.542800] [<8000ea44>] syscall_common+0x34/0x58
[  258.552197]
[  258.555161] ---[ end trace 5910e4a6b837d518 ]---

And this one:
[  259.281306] ------------[ cut here ]------------
[  259.290596] WARNING: CPU: 0 PID: 502 at net/core/stream.c:212 
inet_csk_destroy_sock+0x6c/0x17c
[  259.307833] Modules linked in: rt2800soc rt2800mmio rt2800lib pppoe 
ppp_async nft_fib_inet nf_flow_table_ipv6 nf_flow_table_ipv4 
nf_flow_table_inet rt2x00soc rt2x00mmio rt2x00lib pppox ppp_generic 
nft_reject_ipv6 nft_reject_ipv4 nft_reject_inet nft_reject nft_redir 
nft_quota nft_objref nft_numgen nft_nat nft_masq nft_log nft_limit 
nft_hash nft_flow_offload nft_fib_ipv6 nft_fib_ipv4 nft_fib nft_ct 
nft_counter nft_chain_nat nf_tables nf_nat nf_flow_table nf_conntrack 
mt76x2e mt76x2_common mt76x02_lib mt76 mac80211 lzo cfg80211 slhc 
nfnetlink nf_reject_ipv6 nf_reject_ipv4 nf_log_syslog nf_defrag_ipv6 
nf_defrag_ipv4 lzo_rle lzo_decompress lzo_compress libcrc32c crc_ccitt 
compat sha256_generic libsha256 seqiv jitterentropy_rng drbg hmac cmac 
crypto_acompress leds_gpio gpio_button_hotplug crc32c_generic
[  259.449095] CPU: 0 PID: 502 Comm: napi/phy0-3 Tainted: G        W 
     5.15.95 #0
[  259.464551] Stack : 00000000 00000000 81a21934 80860000 806b0000 
80608730 80e38870 806abe23
[  259.481251]         808633b4 000001f6 00000003 80061c60 80601eac 
00000001 81a218f0 22ee1ee2
[  259.497945]         00000000 00000000 80608730 81a21788 fffff19a 
00000000 00000000 ffffffea
[  259.514639]         00000000 81a21794 0000019a 806b2278 80860000 
00000009 00000000 804651e0
[  259.531332]         00000009 00000003 00000002 00000006 00000018 
803347a4 00000000 80860000
[  259.548030]         ...
[  259.552907] Call Trace:
[  259.557767] [<8000700c>] show_stack+0x28/0xf0
[  259.566489] [<8002622c>] __warn+0x9c/0x124
[  259.574672] [<80026310>] warn_slowpath_fmt+0x5c/0xac
[  259.584584] [<804651e0>] inet_csk_destroy_sock+0x6c/0x17c
[  259.595374] [<80479328>] tcp_reset+0x50/0xb0
[  259.603909] [<8047973c>] tcp_validate_incoming+0x3b4/0x624
[  259.614861] [<8047bc48>] tcp_rcv_state_process+0x32c/0xf80
[  259.625817] [<80521fa0>] tcp_v6_do_rcv+0x290/0x4e4
[  259.635399] [<80522da0>] tcp_v6_rcv+0xbac/0xc3c
[  259.644451] [<804e6798>] ip6_protocol_deliver_rcu+0x118/0x640
[  259.655939] [<804e6d6c>] ip6_input+0x84/0x9c
[  259.664461] [<803e224c>] __netif_receive_skb_one_core+0x44/0x54
[  259.676289] [<803e22ac>] netif_receive_skb+0x34/0xc8
[  259.686201] [<8054ba34>] br_handle_frame_finish+0x330/0x5b0
[  259.697339] [<8054c140>] br_handle_frame+0x48c/0x4fc
[  259.707255] [<803dfa30>] __netif_receive_skb_core.constprop.0+0x268/0xc30
[  259.720807] [<803e04e4>] __netif_receive_skb_list_core+0xec/0x224
[  259.732979] [<803e07c0>] netif_receive_skb_list_internal+0x1a4/0x254
[  259.745670] [<803e0bf8>] napi_complete_done+0x74/0x214
[  259.755957] [<818f2484>] mt76_dma_rx_poll+0x4b0/0x50c [mt76]
[  259.767307] [<803e0e08>] __napi_poll+0x70/0x1f8
[  259.776358] [<803e1034>] napi_threaded_poll+0xa4/0x110
[  259.786618] [<80045ef0>] kthread+0x140/0x164
[  259.795161] [<80002458>] ret_from_kernel_thread+0x14/0x1c
[  259.805942]
[  259.808899] ---[ end trace 5910e4a6b837d519 ]---

Hauke