Hi, This fix can be found here. It was merged to the mac80211 tree. https://patchwork.kernel.org/project/linux-wireless/patch/iwlwifi.20210105165657.613e9a876829.Ia38d27dbebea28bf9c56d70691d243186ede70e7@changeid/ Regards, Ilan. > -----Original Message----- > From: Hans de Goede <hdegoede@xxxxxxxxxx> > Sent: Monday, January 18, 2021 23:09 > To: Peer, Ilan <ilan.peer@xxxxxxxxx>; Johannes Berg > <johannes@xxxxxxxxxxxxxxxx>; David S . Miller <davem@xxxxxxxxxxxxx>; > Jakub Kicinski <kuba@xxxxxxxxxx>; Rojewski, Cezary > <cezary.rojewski@xxxxxxxxx>; Pierre-Louis Bossart <pierre- > louis.bossart@xxxxxxxxxxxxxxx>; Liam Girdwood > <liam.r.girdwood@xxxxxxxxxxxxxxx>; Jie Yang <yang.jie@xxxxxxxxxxxxxxx>; > Mark Brown <broonie@xxxxxxxxxx> > Cc: linux-wireless@xxxxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; linux- > kernel@xxxxxxxxxxxxxxx; alsa-devel@xxxxxxxxxxxxxxxx > Subject: Re: [PATCH] cfg80211: Fix "suspicious RCU usage in > wiphy_apply_custom_regulatory" warning/backtrace > > Hi, > > On 1/5/21 10:24 AM, Peer, Ilan wrote: > > Hi, > > > >> -----Original Message----- > >> From: Hans de Goede <hdegoede@xxxxxxxxxx> > >> Sent: Monday, January 04, 2021 19:07 > >> To: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>; David S . Miller > >> <davem@xxxxxxxxxxxxx>; Jakub Kicinski <kuba@xxxxxxxxxx>; Rojewski, > >> Cezary <cezary.rojewski@xxxxxxxxx>; Pierre-Louis Bossart <pierre- > >> louis.bossart@xxxxxxxxxxxxxxx>; Liam Girdwood > >> <liam.r.girdwood@xxxxxxxxxxxxxxx>; Jie Yang > >> <yang.jie@xxxxxxxxxxxxxxx>; Mark Brown <broonie@xxxxxxxxxx> > >> Cc: Hans de Goede <hdegoede@xxxxxxxxxx>; linux- > >> wireless@xxxxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; linux- > >> kernel@xxxxxxxxxxxxxxx; alsa-devel@xxxxxxxxxxxxxxxx; Peer, Ilan > >> <ilan.peer@xxxxxxxxx> > >> Subject: [PATCH] cfg80211: Fix "suspicious RCU usage in > >> wiphy_apply_custom_regulatory" warning/backtrace > >> > >> Commit beee24695157 ("cfg80211: Save the regulatory domain when > >> setting custom regulatory") adds a get_wiphy_regdom call to > >> wiphy_apply_custom_regulatory. But as the comment above > >> wiphy_apply_custom_regulatory says: > >> "/* Used by drivers prior to wiphy registration */" > >> this function is used by driver's probe function before the wiphy is > >> registered and at this point wiphy->regd will typically by NULL and > >> calling rcu_dereference_rtnl on a NULL pointer causes the following > >> warning/backtrace: > >> > >> ============================= > >> WARNING: suspicious RCU usage > >> 5.11.0-rc1+ #19 Tainted: G W > >> ----------------------------- > >> net/wireless/reg.c:144 suspicious rcu_dereference_check() usage! > >> > >> other info that might help us debug this: > >> > >> rcu_scheduler_active = 2, debug_locks = 1 > >> 2 locks held by kworker/2:0/22: > >> #0: ffff9a4bc104df38 ((wq_completion)events){+.+.}-{0:0}, at: > >> process_one_work+0x1ee/0x570 > >> #1: ffffb6e94010be78 > >> ((work_completion)(&fw_work->work)){+.+.}-{0:0}, > >> at: process_one_work+0x1ee/0x570 > >> > >> stack backtrace: > >> CPU: 2 PID: 22 Comm: kworker/2:0 Tainted: G W 5.11.0-rc1+ #19 > >> Hardware name: LENOVO 60073/INVALID, BIOS 01WT17WW 08/01/2014 > >> Workqueue: events request_firmware_work_func Call Trace: > >> dump_stack+0x8b/0xb0 > >> get_wiphy_regdom+0x57/0x60 [cfg80211] > >> wiphy_apply_custom_regulatory+0xa0/0xf0 [cfg80211] > >> brcmf_cfg80211_attach+0xb02/0x1360 [brcmfmac] > >> brcmf_attach+0x189/0x460 [brcmfmac] > >> brcmf_sdio_firmware_callback+0x78a/0x8f0 [brcmfmac] > >> brcmf_fw_request_done+0x67/0xf0 [brcmfmac] > >> request_firmware_work_func+0x3d/0x70 > >> process_one_work+0x26e/0x570 > >> worker_thread+0x55/0x3c0 > >> ? process_one_work+0x570/0x570 > >> kthread+0x137/0x150 > >> ? __kthread_bind_mask+0x60/0x60 > >> ret_from_fork+0x22/0x30 > >> > >> Add a check for wiphy->regd being NULL before calling > >> get_wiphy_regdom (as is already done in other places) to fix this. > >> > >> wiphy->regd will likely always be NULL when > >> wiphy->wiphy_apply_custom_regulatory > >> gets called, so arguably the tmp = get_wiphy_regdom() and > >> rcu_free_regdom(tmp) calls should simply be dropped, this patch keeps > >> the > >> 2 calls, to allow drivers to call wiphy_apply_custom_regulatory more > >> then once if necessary. > >> > >> Cc: Ilan Peer <ilan.peer@xxxxxxxxx> > >> Fixes: beee24695157 ("cfg80211: Save the regulatory domain when > >> setting custom regulator") > >> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx> > >> --- > >> net/wireless/reg.c | 5 +++-- > >> 1 file changed, 3 insertions(+), 2 deletions(-) > >> > >> diff --git a/net/wireless/reg.c b/net/wireless/reg.c index > >> bb72447ad960..9254b9cbaa21 100644 > >> --- a/net/wireless/reg.c > >> +++ b/net/wireless/reg.c > >> @@ -2547,7 +2547,7 @@ static void handle_band_custom(struct wiphy > >> *wiphy, void wiphy_apply_custom_regulatory(struct wiphy *wiphy, > >> const struct ieee80211_regdomain *regd) { > >> - const struct ieee80211_regdomain *new_regd, *tmp; > >> + const struct ieee80211_regdomain *new_regd, *tmp = NULL; > >> enum nl80211_band band; > >> unsigned int bands_set = 0; > >> > >> @@ -2571,7 +2571,8 @@ void wiphy_apply_custom_regulatory(struct > wiphy > >> *wiphy, > >> if (IS_ERR(new_regd)) > >> return; > >> > >> - tmp = get_wiphy_regdom(wiphy); > >> + if (wiphy->regd) > >> + tmp = get_wiphy_regdom(wiphy); > >> rcu_assign_pointer(wiphy->regd, new_regd); > >> rcu_free_regdom(tmp); > > > > This only fixes the first case where the pointer in NULL and does not handle > the wrong RCU usage in other cases. > > > > I'll prepare a fix for this. > > Any luck with this? This is a regression in 5.11, so this really should be fixed in > a future 5.11-rc and the clock is running out. > > Regards, > > Hans
