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Message-Id: <20201012131115.58843-1-jamie@nuviainc.com>
Date: Mon, 12 Oct 2020 14:11:15 +0100
From: Jamie Iles <jamie@...iainc.com>
To: netdev@...r.kernel.org
Cc: Jamie Iles <jamie@...iainc.com>, Qiushi Wu <wu000273@....edu>,
Jay Vosburgh <j.vosburgh@...il.com>,
Veaceslav Falico <vfalico@...il.com>,
Andy Gospodarek <andy@...yhouse.net>
Subject: [PATCH 3/5] 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@....edu>
Cc: Jay Vosburgh <j.vosburgh@...il.com>
Cc: Veaceslav Falico <vfalico@...il.com>
Cc: Andy Gospodarek <andy@...yhouse.net>
Signed-off-by: Jamie Iles <jamie@...iainc.com>
---
drivers/net/bonding/bond_sysfs_slave.c | 12 ++++++++++++
include/net/bonding.h | 2 ++
2 files changed, 14 insertions(+)
diff --git a/drivers/net/bonding/bond_sysfs_slave.c b/drivers/net/bonding/bond_sysfs_slave.c
index 9b8346638f69..2fdbcf9692c5 100644
--- a/drivers/net/bonding/bond_sysfs_slave.c
+++ b/drivers/net/bonding/bond_sysfs_slave.c
@@ -136,7 +136,15 @@ static const struct sysfs_ops slave_sysfs_ops = {
.show = slave_show,
};
+static void slave_release(struct kobject *kobj)
+{
+ struct slave *slave = to_slave(kobj);
+
+ complete(&slave->kobj_unregister_done);
+}
+
static struct kobj_type slave_ktype = {
+ .release = slave_release,
#ifdef CONFIG_SYSFS
.sysfs_ops = &slave_sysfs_ops,
#endif
@@ -147,10 +155,12 @@ int bond_sysfs_slave_add(struct slave *slave)
const struct slave_attribute **a;
int err;
+ init_completion(&slave->kobj_unregister_done);
err = kobject_init_and_add(&slave->kobj, &slave_ktype,
&(slave->dev->dev.kobj), "bonding_slave");
if (err) {
kobject_put(&slave->kobj);
+ wait_for_completion(&slave->kobj_unregister_done);
return err;
}
@@ -158,6 +168,7 @@ int bond_sysfs_slave_add(struct slave *slave)
err = sysfs_create_file(&slave->kobj, &((*a)->attr));
if (err) {
kobject_put(&slave->kobj);
+ wait_for_completion(&slave->kobj_unregister_done);
return err;
}
}
@@ -173,4 +184,5 @@ void bond_sysfs_slave_del(struct slave *slave)
sysfs_remove_file(&slave->kobj, &((*a)->attr));
kobject_put(&slave->kobj);
+ wait_for_completion(&slave->kobj_unregister_done);
}
diff --git a/include/net/bonding.h b/include/net/bonding.h
index aa854a9c01e2..5db6e8252fed 100644
--- a/include/net/bonding.h
+++ b/include/net/bonding.h
@@ -25,6 +25,7 @@
#include <linux/etherdevice.h>
#include <linux/reciprocal_div.h>
#include <linux/if_link.h>
+#include <linux/completion.h>
#include <net/bond_3ad.h>
#include <net/bond_alb.h>
@@ -177,6 +178,7 @@ struct slave {
#endif
struct delayed_work notify_work;
struct kobject kobj;
+ struct completion kobj_unregister_done;
struct rtnl_link_stats64 slave_stats;
};
--
2.25.1
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