linux/drivers/net/bonding/bond_sysfs_slave.c
Jamie Iles b9ad3e9f5a 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: 07699f9a7c ("bonding: add sysfs /slave dir for bond slave devices.")
Fixes: a068aab422 ("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>
2020-11-21 13:07:00 -08:00

161 lines
3.8 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/* Sysfs attributes of bond slaves
*
* Copyright (c) 2014 Scott Feldman <sfeldma@cumulusnetworks.com>
*/
#include <linux/capability.h>
#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <net/bonding.h>
struct slave_attribute {
struct attribute attr;
ssize_t (*show)(struct slave *, char *);
};
#define SLAVE_ATTR(_name, _mode, _show) \
const struct slave_attribute slave_attr_##_name = { \
.attr = {.name = __stringify(_name), \
.mode = _mode }, \
.show = _show, \
};
#define SLAVE_ATTR_RO(_name) \
SLAVE_ATTR(_name, 0444, _name##_show)
static ssize_t state_show(struct slave *slave, char *buf)
{
switch (bond_slave_state(slave)) {
case BOND_STATE_ACTIVE:
return sprintf(buf, "active\n");
case BOND_STATE_BACKUP:
return sprintf(buf, "backup\n");
default:
return sprintf(buf, "UNKNOWN\n");
}
}
static SLAVE_ATTR_RO(state);
static ssize_t mii_status_show(struct slave *slave, char *buf)
{
return sprintf(buf, "%s\n", bond_slave_link_status(slave->link));
}
static SLAVE_ATTR_RO(mii_status);
static ssize_t link_failure_count_show(struct slave *slave, char *buf)
{
return sprintf(buf, "%d\n", slave->link_failure_count);
}
static SLAVE_ATTR_RO(link_failure_count);
static ssize_t perm_hwaddr_show(struct slave *slave, char *buf)
{
return sprintf(buf, "%*phC\n",
slave->dev->addr_len,
slave->perm_hwaddr);
}
static SLAVE_ATTR_RO(perm_hwaddr);
static ssize_t queue_id_show(struct slave *slave, char *buf)
{
return sprintf(buf, "%d\n", slave->queue_id);
}
static SLAVE_ATTR_RO(queue_id);
static ssize_t ad_aggregator_id_show(struct slave *slave, char *buf)
{
const struct aggregator *agg;
if (BOND_MODE(slave->bond) == BOND_MODE_8023AD) {
agg = SLAVE_AD_INFO(slave)->port.aggregator;
if (agg)
return sprintf(buf, "%d\n",
agg->aggregator_identifier);
}
return sprintf(buf, "N/A\n");
}
static SLAVE_ATTR_RO(ad_aggregator_id);
static ssize_t ad_actor_oper_port_state_show(struct slave *slave, char *buf)
{
const struct port *ad_port;
if (BOND_MODE(slave->bond) == BOND_MODE_8023AD) {
ad_port = &SLAVE_AD_INFO(slave)->port;
if (ad_port->aggregator)
return sprintf(buf, "%u\n",
ad_port->actor_oper_port_state);
}
return sprintf(buf, "N/A\n");
}
static SLAVE_ATTR_RO(ad_actor_oper_port_state);
static ssize_t ad_partner_oper_port_state_show(struct slave *slave, char *buf)
{
const struct port *ad_port;
if (BOND_MODE(slave->bond) == BOND_MODE_8023AD) {
ad_port = &SLAVE_AD_INFO(slave)->port;
if (ad_port->aggregator)
return sprintf(buf, "%u\n",
ad_port->partner_oper.port_state);
}
return sprintf(buf, "N/A\n");
}
static SLAVE_ATTR_RO(ad_partner_oper_port_state);
static const struct slave_attribute *slave_attrs[] = {
&slave_attr_state,
&slave_attr_mii_status,
&slave_attr_link_failure_count,
&slave_attr_perm_hwaddr,
&slave_attr_queue_id,
&slave_attr_ad_aggregator_id,
&slave_attr_ad_actor_oper_port_state,
&slave_attr_ad_partner_oper_port_state,
NULL
};
#define to_slave_attr(_at) container_of(_at, struct slave_attribute, attr)
static ssize_t slave_show(struct kobject *kobj,
struct attribute *attr, char *buf)
{
struct slave_attribute *slave_attr = to_slave_attr(attr);
struct slave *slave = to_slave(kobj);
return slave_attr->show(slave, buf);
}
const struct sysfs_ops slave_sysfs_ops = {
.show = slave_show,
};
int bond_sysfs_slave_add(struct slave *slave)
{
const struct slave_attribute **a;
int err;
for (a = slave_attrs; *a; ++a) {
err = sysfs_create_file(&slave->kobj, &((*a)->attr));
if (err) {
kobject_put(&slave->kobj);
return err;
}
}
return 0;
}
void bond_sysfs_slave_del(struct slave *slave)
{
const struct slave_attribute **a;
for (a = slave_attrs; *a; ++a)
sysfs_remove_file(&slave->kobj, &((*a)->attr));
}