Message-ID: <87sexbsvqj.fsf@toke.dk>
Date: Mon, 17 Jun 2024 12:35:00 +0200
From: Toke Høiland-Jørgensen <toke@...e.dk>
To: Eric Dumazet <edumazet@...gle.com>, "David S . Miller"
 <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
 <pabeni@...hat.com>, Johannes Berg <johannes@...solutions.net>
Cc: linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
 eric.dumazet@...il.com, Eric Dumazet <edumazet@...gle.com>
Subject: Re: [PATCH net] wifi: cfg80211: restrict NL80211_ATTR_TXQ_QUANTUM
 values

Eric Dumazet <edumazet@...gle.com> writes:

> syzbot is able to trigger softlockups, setting NL80211_ATTR_TXQ_QUANTUM
> to 2^31.
>
> We had a similar issue in sch_fq, fixed with commit
> d9e15a273306 ("pkt_sched: fq: do not accept silly TCA_FQ_QUANTUM")
>
> watchdog: BUG: soft lockup - CPU#1 stuck for 26s! [kworker/1:0:24]
> Modules linked in:
> irq event stamp: 131135
>  hardirqs last  enabled at (131134): [<ffff80008ae8778c>] __exit_to_kernel_mode arch/arm64/kernel/entry-common.c:85 [inline]
>  hardirqs last  enabled at (131134): [<ffff80008ae8778c>] exit_to_kernel_mode+0xdc/0x10c arch/arm64/kernel/entry-common.c:95
>  hardirqs last disabled at (131135): [<ffff80008ae85378>] __el1_irq arch/arm64/kernel/entry-common.c:533 [inline]
>  hardirqs last disabled at (131135): [<ffff80008ae85378>] el1_interrupt+0x24/0x68 arch/arm64/kernel/entry-common.c:551
>  softirqs last  enabled at (125892): [<ffff80008907e82c>] neigh_hh_init net/core/neighbour.c:1538 [inline]
>  softirqs last  enabled at (125892): [<ffff80008907e82c>] neigh_resolve_output+0x268/0x658 net/core/neighbour.c:1553
>  softirqs last disabled at (125896): [<ffff80008904166c>] local_bh_disable+0x10/0x34 include/linux/bottom_half.h:19
> CPU: 1 PID: 24 Comm: kworker/1:0 Not tainted 6.9.0-rc7-syzkaller-gfda5695d692c #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
> Workqueue: mld mld_ifc_work
> pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
>  pc : __list_del include/linux/list.h:195 [inline]
>  pc : __list_del_entry include/linux/list.h:218 [inline]
>  pc : list_move_tail include/linux/list.h:310 [inline]
>  pc : fq_tin_dequeue include/net/fq_impl.h:112 [inline]
>  pc : ieee80211_tx_dequeue+0x6b8/0x3b4c net/mac80211/tx.c:3854
>  lr : __list_del_entry include/linux/list.h:218 [inline]
>  lr : list_move_tail include/linux/list.h:310 [inline]
>  lr : fq_tin_dequeue include/net/fq_impl.h:112 [inline]
>  lr : ieee80211_tx_dequeue+0x67c/0x3b4c net/mac80211/tx.c:3854
> sp : ffff800093d36700
> x29: ffff800093d36a60 x28: ffff800093d36960 x27: dfff800000000000
> x26: ffff0000d800ad50 x25: ffff0000d800abe0 x24: ffff0000d800abf0
> x23: ffff0000e0032468 x22: ffff0000e00324d4 x21: ffff0000d800abf0
> x20: ffff0000d800abf8 x19: ffff0000d800abf0 x18: ffff800093d363c0
> x17: 000000000000d476 x16: ffff8000805519dc x15: ffff7000127a6cc8
> x14: 1ffff000127a6cc8 x13: 0000000000000004 x12: ffffffffffffffff
> x11: ffff7000127a6cc8 x10: 0000000000ff0100 x9 : 0000000000000000
> x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0000000000000000
> x5 : ffff80009287aa08 x4 : 0000000000000008 x3 : ffff80008034c7fc
> x2 : ffff0000e0032468 x1 : 00000000da0e46b8 x0 : ffff0000e0032470
> Call trace:
>   __list_del include/linux/list.h:195 [inline]
>   __list_del_entry include/linux/list.h:218 [inline]
>   list_move_tail include/linux/list.h:310 [inline]
>   fq_tin_dequeue include/net/fq_impl.h:112 [inline]
>   ieee80211_tx_dequeue+0x6b8/0x3b4c net/mac80211/tx.c:3854
>   wake_tx_push_queue net/mac80211/util.c:294 [inline]
>   ieee80211_handle_wake_tx_queue+0x118/0x274 net/mac80211/util.c:315
>   drv_wake_tx_queue net/mac80211/driver-ops.h:1350 [inline]
>   schedule_and_wake_txq net/mac80211/driver-ops.h:1357 [inline]
>   ieee80211_queue_skb+0x18e8/0x2244 net/mac80211/tx.c:1664
>   ieee80211_tx+0x260/0x400 net/mac80211/tx.c:1966
>   ieee80211_xmit+0x278/0x354 net/mac80211/tx.c:2062
>   __ieee80211_subif_start_xmit+0xab8/0x122c net/mac80211/tx.c:4338
>   ieee80211_subif_start_xmit+0xe0/0x438 net/mac80211/tx.c:4532
>   __netdev_start_xmit include/linux/netdevice.h:4903 [inline]
>   netdev_start_xmit include/linux/netdevice.h:4917 [inline]
>   xmit_one net/core/dev.c:3531 [inline]
>   dev_hard_start_xmit+0x27c/0x938 net/core/dev.c:3547
>   __dev_queue_xmit+0x1678/0x33fc net/core/dev.c:4341
>   dev_queue_xmit include/linux/netdevice.h:3091 [inline]
>   neigh_resolve_output+0x558/0x658 net/core/neighbour.c:1563
>   neigh_output include/net/neighbour.h:542 [inline]
>   ip6_finish_output2+0x104c/0x1ee8 net/ipv6/ip6_output.c:137
>   ip6_finish_output+0x428/0x7a0 net/ipv6/ip6_output.c:222
>   NF_HOOK_COND include/linux/netfilter.h:303 [inline]
>   ip6_output+0x270/0x594 net/ipv6/ip6_output.c:243
>   dst_output include/net/dst.h:450 [inline]
>   NF_HOOK+0x160/0x4f0 include/linux/netfilter.h:314
>   mld_sendpack+0x7b4/0x10f4 net/ipv6/mcast.c:1818
>   mld_send_cr net/ipv6/mcast.c:2119 [inline]
>   mld_ifc_work+0x840/0xd0c net/ipv6/mcast.c:2650
>   process_one_work+0x7b8/0x15d4 kernel/workqueue.c:3267
>   process_scheduled_works kernel/workqueue.c:3348 [inline]
>   worker_thread+0x938/0xef4 kernel/workqueue.c:3429
>   kthread+0x288/0x310 kernel/kthread.c:388
>   ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860
>
> Fixes: 52539ca89f36 ("cfg80211: Expose TXQ stats and parameters to userspace")
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Signed-off-by: Toke Høiland-Jørgensen <toke@...e.dk>

Hmm, extraneous s-o-b? :)

> ---
>  net/wireless/nl80211.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
> index 3c0bca4238d357c01b6fe92bb0f2b2b8a2917725..72c7bf55858166b8fc12114f090bf085d652db6b 100644
> --- a/net/wireless/nl80211.c
> +++ b/net/wireless/nl80211.c
> @@ -468,6 +468,10 @@ static const struct netlink_range_validation nl80211_punct_bitmap_range = {
>  	.max = 0xffff,
>  };
>  
> +static const struct netlink_range_validation q_range = {
> +	.max = INT_MAX,
> +};

The corresponding fixes to sch_fq and fq_codel use a limit of 1<<20;
INT_MAX is a bit above that, won't that still lead to issues?

-Toke

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