From: Jamie Iles jamie@nuviainc.com
[ Upstream commit b9ad3e9f5a7a760ab068e33e1f18d240ba32ce92 ]
syzkaller found that with CONFIG_DEBUG_KOBJECT_RELEASE=y, releasing a struct slave device could result in the following splat:
kobject: 'bonding_slave' (00000000cecdd4fe): kobject_release, parent 0000000074ceb2b2 (delayed 1000) bond0 (unregistering): (slave bond_slave_1): Releasing backup interface ------------[ cut here ]------------ ODEBUG: free active (active state 0) object type: timer_list hint: workqueue_select_cpu_near kernel/workqueue.c:1549 [inline] ODEBUG: free active (active state 0) object type: timer_list hint: delayed_work_timer_fn+0x0/0x98 kernel/workqueue.c:1600 WARNING: CPU: 1 PID: 842 at lib/debugobjects.c:485 debug_print_object+0x180/0x240 lib/debugobjects.c:485 Kernel panic - not syncing: panic_on_warn set ... CPU: 1 PID: 842 Comm: kworker/u4:4 Tainted: G S 5.9.0-rc8+ #96 Hardware name: linux,dummy-virt (DT) Workqueue: netns cleanup_net Call trace: dump_backtrace+0x0/0x4d8 include/linux/bitmap.h:239 show_stack+0x34/0x48 arch/arm64/kernel/traps.c:142 __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x174/0x1f8 lib/dump_stack.c:118 panic+0x360/0x7a0 kernel/panic.c:231 __warn+0x244/0x2ec kernel/panic.c:600 report_bug+0x240/0x398 lib/bug.c:198 bug_handler+0x50/0xc0 arch/arm64/kernel/traps.c:974 call_break_hook+0x160/0x1d8 arch/arm64/kernel/debug-monitors.c:322 brk_handler+0x30/0xc0 arch/arm64/kernel/debug-monitors.c:329 do_debug_exception+0x184/0x340 arch/arm64/mm/fault.c:864 el1_dbg+0x48/0xb0 arch/arm64/kernel/entry-common.c:65 el1_sync_handler+0x170/0x1c8 arch/arm64/kernel/entry-common.c:93 el1_sync+0x80/0x100 arch/arm64/kernel/entry.S:594 debug_print_object+0x180/0x240 lib/debugobjects.c:485 __debug_check_no_obj_freed lib/debugobjects.c:967 [inline] debug_check_no_obj_freed+0x200/0x430 lib/debugobjects.c:998 slab_free_hook mm/slub.c:1536 [inline] slab_free_freelist_hook+0x190/0x210 mm/slub.c:1577 slab_free mm/slub.c:3138 [inline] kfree+0x13c/0x460 mm/slub.c:4119 bond_free_slave+0x8c/0xf8 drivers/net/bonding/bond_main.c:1492 __bond_release_one+0xe0c/0xec8 drivers/net/bonding/bond_main.c:2190 bond_slave_netdev_event drivers/net/bonding/bond_main.c:3309 [inline] bond_netdev_event+0x8f0/0xa70 drivers/net/bonding/bond_main.c:3420 notifier_call_chain+0xf0/0x200 kernel/notifier.c:83 __raw_notifier_call_chain kernel/notifier.c:361 [inline] raw_notifier_call_chain+0x44/0x58 kernel/notifier.c:368 call_netdevice_notifiers_info+0xbc/0x150 net/core/dev.c:2033 call_netdevice_notifiers_extack net/core/dev.c:2045 [inline] call_netdevice_notifiers net/core/dev.c:2059 [inline] rollback_registered_many+0x6a4/0xec0 net/core/dev.c:9347 unregister_netdevice_many.part.0+0x2c/0x1c0 net/core/dev.c:10509 unregister_netdevice_many net/core/dev.c:10508 [inline] default_device_exit_batch+0x294/0x338 net/core/dev.c:10992 ops_exit_list.isra.0+0xec/0x150 net/core/net_namespace.c:189 cleanup_net+0x44c/0x888 net/core/net_namespace.c:603 process_one_work+0x96c/0x18c0 kernel/workqueue.c:2269 worker_thread+0x3f0/0xc30 kernel/workqueue.c:2415 kthread+0x390/0x498 kernel/kthread.c:292 ret_from_fork+0x10/0x18 arch/arm64/kernel/entry.S:925
This is a potential use-after-free if the sysfs nodes are being accessed whilst removing the struct slave, so wait for the object destruction to complete before freeing the struct slave itself.
Fixes: 07699f9a7c8d ("bonding: add sysfs /slave dir for bond slave devices.") Fixes: a068aab42258 ("bonding: Fix reference count leak in bond_sysfs_slave_add.") Cc: Qiushi Wu wu000273@umn.edu Cc: Jay Vosburgh j.vosburgh@gmail.com Cc: Veaceslav Falico vfalico@gmail.com Cc: Andy Gospodarek andy@greyhouse.net Signed-off-by: Jamie Iles jamie@nuviainc.com Reviewed-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Link: https://lore.kernel.org/r/20201120142827.879226-1-jamie@nuviainc.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/bonding/bond_main.c | 61 +++++++++++++++++++++++---------- drivers/net/bonding/bond_sysfs_slave.c | 18 --------- include/net/bonding.h | 8 ++++ 3 files changed, 52 insertions(+), 35 deletions(-)
--- a/drivers/net/bonding/bond_main.c +++ b/drivers/net/bonding/bond_main.c @@ -1253,7 +1253,39 @@ static void bond_upper_dev_unlink(struct rtmsg_ifinfo(RTM_NEWLINK, slave->dev, IFF_SLAVE, GFP_KERNEL); }
-static struct slave *bond_alloc_slave(struct bonding *bond) +static void slave_kobj_release(struct kobject *kobj) +{ + struct slave *slave = to_slave(kobj); + struct bonding *bond = bond_get_bond_by_slave(slave); + + cancel_delayed_work_sync(&slave->notify_work); + if (BOND_MODE(bond) == BOND_MODE_8023AD) + kfree(SLAVE_AD_INFO(slave)); + + kfree(slave); +} + +static struct kobj_type slave_ktype = { + .release = slave_kobj_release, +#ifdef CONFIG_SYSFS + .sysfs_ops = &slave_sysfs_ops, +#endif +}; + +static int bond_kobj_init(struct slave *slave) +{ + int err; + + err = kobject_init_and_add(&slave->kobj, &slave_ktype, + &(slave->dev->dev.kobj), "bonding_slave"); + if (err) + kobject_put(&slave->kobj); + + return err; +} + +static struct slave *bond_alloc_slave(struct bonding *bond, + struct net_device *slave_dev) { struct slave *slave = NULL;
@@ -1261,11 +1293,17 @@ static struct slave *bond_alloc_slave(st if (!slave) return NULL;
+ slave->bond = bond; + slave->dev = slave_dev; + + if (bond_kobj_init(slave)) + return NULL; + if (BOND_MODE(bond) == BOND_MODE_8023AD) { SLAVE_AD_INFO(slave) = kzalloc(sizeof(struct ad_slave_info), GFP_KERNEL); if (!SLAVE_AD_INFO(slave)) { - kfree(slave); + kobject_put(&slave->kobj); return NULL; } } @@ -1274,17 +1312,6 @@ static struct slave *bond_alloc_slave(st return slave; }
-static void bond_free_slave(struct slave *slave) -{ - struct bonding *bond = bond_get_bond_by_slave(slave); - - cancel_delayed_work_sync(&slave->notify_work); - if (BOND_MODE(bond) == BOND_MODE_8023AD) - kfree(SLAVE_AD_INFO(slave)); - - kfree(slave); -} - static void bond_fill_ifbond(struct bonding *bond, struct ifbond *info) { info->bond_mode = BOND_MODE(bond); @@ -1464,14 +1491,12 @@ int bond_enslave(struct net_device *bond bond->dev->addr_assign_type == NET_ADDR_RANDOM) bond_set_dev_addr(bond->dev, slave_dev);
- new_slave = bond_alloc_slave(bond); + new_slave = bond_alloc_slave(bond, slave_dev); if (!new_slave) { res = -ENOMEM; goto err_undo_flags; }
- new_slave->bond = bond; - new_slave->dev = slave_dev; /* Set the new_slave's queue_id to be zero. Queue ID mapping * is set via sysfs or module option if desired. */ @@ -1802,7 +1827,7 @@ err_restore_mtu: dev_set_mtu(slave_dev, new_slave->original_mtu);
err_free: - bond_free_slave(new_slave); + kobject_put(&new_slave->kobj);
err_undo_flags: /* Enslave of first slave has failed and we need to fix master's mac */ @@ -1990,7 +2015,7 @@ static int __bond_release_one(struct net if (!netif_is_bond_master(slave_dev)) slave_dev->priv_flags &= ~IFF_BONDING;
- bond_free_slave(slave); + kobject_put(&slave->kobj);
return 0; } --- a/drivers/net/bonding/bond_sysfs_slave.c +++ b/drivers/net/bonding/bond_sysfs_slave.c @@ -125,7 +125,6 @@ static const struct slave_attribute *sla };
#define to_slave_attr(_at) container_of(_at, struct slave_attribute, attr) -#define to_slave(obj) container_of(obj, struct slave, kobj)
static ssize_t slave_show(struct kobject *kobj, struct attribute *attr, char *buf) @@ -136,28 +135,15 @@ static ssize_t slave_show(struct kobject return slave_attr->show(slave, buf); }
-static const struct sysfs_ops slave_sysfs_ops = { +const struct sysfs_ops slave_sysfs_ops = { .show = slave_show, };
-static struct kobj_type slave_ktype = { -#ifdef CONFIG_SYSFS - .sysfs_ops = &slave_sysfs_ops, -#endif -}; - int bond_sysfs_slave_add(struct slave *slave) { const struct slave_attribute **a; int err;
- err = kobject_init_and_add(&slave->kobj, &slave_ktype, - &(slave->dev->dev.kobj), "bonding_slave"); - if (err) { - kobject_put(&slave->kobj); - return err; - } - for (a = slave_attrs; *a; ++a) { err = sysfs_create_file(&slave->kobj, &((*a)->attr)); if (err) { @@ -175,6 +161,4 @@ void bond_sysfs_slave_del(struct slave *
for (a = slave_attrs; *a; ++a) sysfs_remove_file(&slave->kobj, &((*a)->attr)); - - kobject_put(&slave->kobj); } --- a/include/net/bonding.h +++ b/include/net/bonding.h @@ -170,6 +170,11 @@ struct slave { struct rtnl_link_stats64 slave_stats; };
+static inline struct slave *to_slave(struct kobject *kobj) +{ + return container_of(kobj, struct slave, kobj); +} + struct bond_up_slave { unsigned int count; struct rcu_head rcu; @@ -716,6 +721,9 @@ extern struct bond_parm_tbl ad_select_tb /* exported from bond_netlink.c */ extern struct rtnl_link_ops bond_link_ops;
+/* exported from bond_sysfs_slave.c */ +extern const struct sysfs_ops slave_sysfs_ops; + static inline void bond_tx_drop(struct net_device *dev, struct sk_buff *skb) { atomic_long_inc(&dev->tx_dropped);