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Date: Thu, 21 Apr 2022 08:12:58 +0300 From: Leon Romanovsky <leon@...nel.org> To: Ivan Vecera <ivecera@...hat.com> Cc: netdev@...r.kernel.org, poros@...hat.com, mschmidt@...hat.com, Jesse Brandeburg <jesse.brandeburg@...el.com>, Tony Nguyen <anthony.l.nguyen@...el.com>, "David S. Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, Dave Ertman <david.m.ertman@...el.com>, Shiraz Saleem <shiraz.saleem@...el.com>, "moderated list:INTEL ETHERNET DRIVERS" <intel-wired-lan@...ts.osuosl.org>, open list <linux-kernel@...r.kernel.org> Subject: Re: [PATCH net v2] ice: Fix race during aux device (un)plugging On Wed, Apr 20, 2022 at 05:02:59PM +0200, Ivan Vecera wrote: > Function ice_plug_aux_dev() assigns pf->adev field too early prior > aux device initialization and on other side ice_unplug_aux_dev() > starts aux device deinit and at the end assigns NULL to pf->adev. > This is wrong because pf->adev should always be non-NULL only when > aux device is fully initialized and ready. This wrong order causes > a crash when ice_send_event_to_aux() call occurs because that function > depends on non-NULL value of pf->adev and does not assume that > aux device is half-initialized or half-destroyed. > After order correction the race window is tiny but it is still there, > as Leon mentioned and manipulation with pf->adev needs to be protected > by mutex. > > Fix (un-)plugging functions so pf->adev field is set after aux device > init and prior aux device destroy and protect pf->adev assignment by > new mutex. This mutex is also held during ice_send_event_to_aux() > call to ensure that aux device is valid during that call. Device > lock used ice_send_event_to_aux() to avoid its concurrent run can > be removed as this is secured by that mutex. > > Reproducer: > cycle=1 > while :;do > echo "#### Cycle: $cycle" > > ip link set ens7f0 mtu 9000 > ip link add bond0 type bond mode 1 miimon 100 > ip link set bond0 up > ifenslave bond0 ens7f0 > ip link set bond0 mtu 9000 > ethtool -L ens7f0 combined 1 > ip link del bond0 > ip link set ens7f0 mtu 1500 > sleep 1 > > let cycle++ > done > > In short when the device is added/removed to/from bond the aux device > is unplugged/plugged. When MTU of the device is changed an event is > sent to aux device asynchronously. This can race with (un)plugging > operation and because pf->adev is set too early (plug) or too late > (unplug) the function ice_send_event_to_aux() can touch uninitialized > or destroyed fields. In the case of crash below pf->adev->dev.mutex. > > Crash: > [ 53.372066] bond0: (slave ens7f0): making interface the new active one > [ 53.378622] bond0: (slave ens7f0): Enslaving as an active interface with an u > p link > [ 53.386294] IPv6: ADDRCONF(NETDEV_CHANGE): bond0: link becomes ready > [ 53.549104] bond0: (slave ens7f1): Enslaving as a backup interface with an up > link > [ 54.118906] ice 0000:ca:00.0 ens7f0: Number of in use tx queues changed inval > idating tc mappings. Priority traffic classification disabled! > [ 54.233374] ice 0000:ca:00.1 ens7f1: Number of in use tx queues changed inval > idating tc mappings. Priority traffic classification disabled! > [ 54.248204] bond0: (slave ens7f0): Releasing backup interface > [ 54.253955] bond0: (slave ens7f1): making interface the new active one > [ 54.274875] bond0: (slave ens7f1): Releasing backup interface > [ 54.289153] bond0 (unregistering): Released all slaves > [ 55.383179] MII link monitoring set to 100 ms > [ 55.398696] bond0: (slave ens7f0): making interface the new active one > [ 55.405241] BUG: kernel NULL pointer dereference, address: 0000000000000080 > [ 55.405289] bond0: (slave ens7f0): Enslaving as an active interface with an u > p link > [ 55.412198] #PF: supervisor write access in kernel mode > [ 55.412200] #PF: error_code(0x0002) - not-present page > [ 55.412201] PGD 25d2ad067 P4D 0 > [ 55.412204] Oops: 0002 [#1] PREEMPT SMP NOPTI > [ 55.412207] CPU: 0 PID: 403 Comm: kworker/0:2 Kdump: loaded Tainted: G S > 5.17.0-13579-g57f2d6540f03 #1 > [ 55.429094] bond0: (slave ens7f1): Enslaving as a backup interface with an up > link > [ 55.430224] Hardware name: Dell Inc. PowerEdge R750/06V45N, BIOS 1.4.4 10/07/ > 2021 > [ 55.430226] Workqueue: ice ice_service_task [ice] > [ 55.468169] RIP: 0010:mutex_unlock+0x10/0x20 > [ 55.472439] Code: 0f b1 13 74 96 eb e0 4c 89 ee eb d8 e8 79 54 ff ff 66 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 65 48 8b 04 25 40 ef 01 00 31 d2 <f0> 48 0f b1 17 75 01 c3 e9 e3 fe ff ff 0f 1f 00 0f 1f 44 00 00 48 > [ 55.491186] RSP: 0018:ff4454230d7d7e28 EFLAGS: 00010246 > [ 55.496413] RAX: ff1a79b208b08000 RBX: ff1a79b2182e8880 RCX: 0000000000000001 > [ 55.503545] RDX: 0000000000000000 RSI: ff4454230d7d7db0 RDI: 0000000000000080 > [ 55.510678] RBP: ff1a79d1c7e48b68 R08: ff4454230d7d7db0 R09: 0000000000000041 > [ 55.517812] R10: 00000000000000a5 R11: 00000000000006e6 R12: ff1a79d1c7e48bc0 > [ 55.524945] R13: 0000000000000000 R14: ff1a79d0ffc305c0 R15: 0000000000000000 > [ 55.532076] FS: 0000000000000000(0000) GS:ff1a79d0ffc00000(0000) knlGS:0000000000000000 > [ 55.540163] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 55.545908] CR2: 0000000000000080 CR3: 00000003487ae003 CR4: 0000000000771ef0 > [ 55.553041] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > [ 55.560173] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > [ 55.567305] PKRU: 55555554 > [ 55.570018] Call Trace: > [ 55.572474] <TASK> > [ 55.574579] ice_service_task+0xaab/0xef0 [ice] > [ 55.579130] process_one_work+0x1c5/0x390 > [ 55.583141] ? process_one_work+0x390/0x390 > [ 55.587326] worker_thread+0x30/0x360 > [ 55.590994] ? process_one_work+0x390/0x390 > [ 55.595180] kthread+0xe6/0x110 > [ 55.598325] ? kthread_complete_and_exit+0x20/0x20 > [ 55.603116] ret_from_fork+0x1f/0x30 > [ 55.606698] </TASK> > > Fixes: f9f5301e7e2d ("ice: Register auxiliary device to provide RDMA") > Cc: Leon Romanovsky <leon@...nel.org> > Signed-off-by: Ivan Vecera <ivecera@...hat.com> > --- > drivers/net/ethernet/intel/ice/ice.h | 1 + > drivers/net/ethernet/intel/ice/ice_idc.c | 33 ++++++++++++++--------- > drivers/net/ethernet/intel/ice/ice_main.c | 2 ++ > 3 files changed, 23 insertions(+), 13 deletions(-) > > diff --git a/drivers/net/ethernet/intel/ice/ice.h b/drivers/net/ethernet/intel/ice/ice.h > index 8ed3c9ab7ff7..a895e3a8e988 100644 > --- a/drivers/net/ethernet/intel/ice/ice.h > +++ b/drivers/net/ethernet/intel/ice/ice.h > @@ -540,6 +540,7 @@ struct ice_pf { > struct mutex avail_q_mutex; /* protects access to avail_[rx|tx]qs */ > struct mutex sw_mutex; /* lock for protecting VSI alloc flow */ > struct mutex tc_mutex; /* lock to protect TC changes */ > + struct mutex adev_mutex; /* lock to protect aux device access */ > u32 msg_enable; > struct ice_ptp ptp; > struct tty_driver *ice_gnss_tty_driver; > diff --git a/drivers/net/ethernet/intel/ice/ice_idc.c b/drivers/net/ethernet/intel/ice/ice_idc.c > index 25a436d342c2..aef07accd63b 100644 > --- a/drivers/net/ethernet/intel/ice/ice_idc.c > +++ b/drivers/net/ethernet/intel/ice/ice_idc.c > @@ -10,13 +10,15 @@ > * ice_get_auxiliary_drv - retrieve iidc_auxiliary_drv struct > * @pf: pointer to PF struct > * > - * This function has to be called with a device_lock on the > - * pf->adev.dev to avoid race conditions. > + * This function has to be called with pf->adev_mutex held > + * to avoid race conditions. > */ > static struct iidc_auxiliary_drv *ice_get_auxiliary_drv(struct ice_pf *pf) > { > struct auxiliary_device *adev; > > + BUG_ON(!mutex_is_locked(&pf->adev_mutex)); Please don't add BUG_ON() in driver code. I think that you are looking for lockdep_assert_held(&pf->adev_mutex). Thanks
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