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authorJamie Iles <jamie@nuviainc.com>2020-11-20 15:28:27 +0100
committerJakub Kicinski <kuba@kernel.org>2020-11-21 22:07:00 +0100
commitb9ad3e9f5a7a760ab068e33e1f18d240ba32ce92 (patch)
tree190458a6bdd274cdfad65071580a7f3889c040cf /drivers/net/bonding/bond_main.c
parentMerge branch 's390-qeth-fixes-2020-11-20' (diff)
downloadlinux-b9ad3e9f5a7a760ab068e33e1f18d240ba32ce92.tar.xz
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bonding: wait for sysfs kobject destruction before freeing struct slave
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>
Diffstat (limited to 'drivers/net/bonding/bond_main.c')
-rw-r--r--drivers/net/bonding/bond_main.c61
1 files changed, 43 insertions, 18 deletions
diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 84ecbc6fa0ff..47afc5938c26 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -1460,7 +1460,39 @@ static void bond_upper_dev_unlink(struct bonding *bond, struct slave *slave)
slave->dev->flags &= ~IFF_SLAVE;
}
-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;
@@ -1468,11 +1500,17 @@ static struct slave *bond_alloc_slave(struct bonding *bond)
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;
}
}
@@ -1481,17 +1519,6 @@ static struct slave *bond_alloc_slave(struct bonding *bond)
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);
@@ -1678,14 +1705,12 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev,
goto err_undo_flags;
}
- 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.
*/
@@ -2007,7 +2032,7 @@ 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 */
@@ -2187,7 +2212,7 @@ static int __bond_release_one(struct net_device *bond_dev,
if (!netif_is_bond_master(slave_dev))
slave_dev->priv_flags &= ~IFF_BONDING;
- bond_free_slave(slave);
+ kobject_put(&slave->kobj);
return 0;
}