| Message ID | 20210104170713.66956-1-hdegoede@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | cfg80211: Fix "suspicious RCU usage in wiphy_apply_custom_regulatory" warning/backtrace | expand |
Hi, > -----Original Message----- > From: Hans de Goede <hdegoede@redhat.com> > Sent: Monday, January 04, 2021 19:07 > To: Johannes Berg <johannes@sipsolutions.net>; David S . Miller > <davem@davemloft.net>; Jakub Kicinski <kuba@kernel.org>; Rojewski, > Cezary <cezary.rojewski@intel.com>; Pierre-Louis Bossart <pierre- > louis.bossart@linux.intel.com>; Liam Girdwood > <liam.r.girdwood@linux.intel.com>; Jie Yang <yang.jie@linux.intel.com>; > Mark Brown <broonie@kernel.org> > Cc: Hans de Goede <hdegoede@redhat.com>; linux- > wireless@vger.kernel.org; netdev@vger.kernel.org; linux- > kernel@vger.kernel.org; alsa-devel@alsa-project.org; Peer, Ilan > <ilan.peer@intel.com> > 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@intel.com> > Fixes: beee24695157 ("cfg80211: Save the regulatory domain when setting > custom regulator") > Signed-off-by: Hans de Goede <hdegoede@redhat.com> > --- > 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. Thanks for addressing the bug, Ilan.
Hi, On 1/5/21 10:24 AM, Peer, Ilan wrote: > Hi, > >> -----Original Message----- >> From: Hans de Goede <hdegoede@redhat.com> >> Sent: Monday, January 04, 2021 19:07 >> To: Johannes Berg <johannes@sipsolutions.net>; David S . Miller >> <davem@davemloft.net>; Jakub Kicinski <kuba@kernel.org>; Rojewski, >> Cezary <cezary.rojewski@intel.com>; Pierre-Louis Bossart <pierre- >> louis.bossart@linux.intel.com>; Liam Girdwood >> <liam.r.girdwood@linux.intel.com>; Jie Yang <yang.jie@linux.intel.com>; >> Mark Brown <broonie@kernel.org> >> Cc: Hans de Goede <hdegoede@redhat.com>; linux- >> wireless@vger.kernel.org; netdev@vger.kernel.org; linux- >> kernel@vger.kernel.org; alsa-devel@alsa-project.org; Peer, Ilan >> <ilan.peer@intel.com> >> 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@intel.com> >> Fixes: beee24695157 ("cfg80211: Save the regulatory domain when setting >> custom regulator") >> Signed-off-by: Hans de Goede <hdegoede@redhat.com> >> --- >> 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
============================= 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_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@intel.com> Fixes: beee24695157 ("cfg80211: Save the regulatory domain when setting custom regulator") Signed-off-by: Hans de Goede <hdegoede@redhat.com> --- 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); }
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: