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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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3c8fc87820
syszbot found an interesting use-after-free [1] happening
while IPv4 fragment rhashtable was destroyed at netns dismantle.
While no insertions can possibly happen at the time a dismantling
netns is destroying this rhashtable, timers can still fire and
attempt to remove elements from this rhashtable.
This is forbidden, since rhashtable_free_and_destroy() has
no synchronization against concurrent inserts and deletes.
Add a new fqdir->dead flag so that timers do not attempt
a rhashtable_remove_fast() operation.
We also have to respect an RCU grace period before starting
the rhashtable_free_and_destroy() from process context,
thus we use rcu_work infrastructure.
This is a refinement of a prior rough attempt to fix this bug :
https://marc.info/?l=linux-netdev&m=153845936820900&w=2
Since the rhashtable cleanup is now deferred to a work queue,
netns dismantles should be slightly faster.
[1]
BUG: KASAN: use-after-free in __read_once_size include/linux/compiler.h:194 [inline]
BUG: KASAN: use-after-free in rhashtable_last_table+0x162/0x180 lib/rhashtable.c:212
Read of size 8 at addr ffff8880a6497b70 by task kworker/0:0/5
CPU: 0 PID: 5 Comm: kworker/0:0 Not tainted 5.2.0-rc1+ #2
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events rht_deferred_worker
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x172/0x1f0 lib/dump_stack.c:113
print_address_description.cold+0x7c/0x20d mm/kasan/report.c:188
__kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317
kasan_report+0x12/0x20 mm/kasan/common.c:614
__asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132
__read_once_size include/linux/compiler.h:194 [inline]
rhashtable_last_table+0x162/0x180 lib/rhashtable.c:212
rht_deferred_worker+0x111/0x2030 lib/rhashtable.c:411
process_one_work+0x989/0x1790 kernel/workqueue.c:2269
worker_thread+0x98/0xe40 kernel/workqueue.c:2415
kthread+0x354/0x420 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Allocated by task 32687:
save_stack+0x23/0x90 mm/kasan/common.c:71
set_track mm/kasan/common.c:79 [inline]
__kasan_kmalloc mm/kasan/common.c:489 [inline]
__kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:462
kasan_kmalloc+0x9/0x10 mm/kasan/common.c:503
__do_kmalloc_node mm/slab.c:3620 [inline]
__kmalloc_node+0x4e/0x70 mm/slab.c:3627
kmalloc_node include/linux/slab.h:590 [inline]
kvmalloc_node+0x68/0x100 mm/util.c:431
kvmalloc include/linux/mm.h:637 [inline]
kvzalloc include/linux/mm.h:645 [inline]
bucket_table_alloc+0x90/0x480 lib/rhashtable.c:178
rhashtable_init+0x3f4/0x7b0 lib/rhashtable.c:1057
inet_frags_init_net include/net/inet_frag.h:109 [inline]
ipv4_frags_init_net+0x182/0x410 net/ipv4/ip_fragment.c:683
ops_init+0xb3/0x410 net/core/net_namespace.c:130
setup_net+0x2d3/0x740 net/core/net_namespace.c:316
copy_net_ns+0x1df/0x340 net/core/net_namespace.c:439
create_new_namespaces+0x400/0x7b0 kernel/nsproxy.c:107
unshare_nsproxy_namespaces+0xc2/0x200 kernel/nsproxy.c:206
ksys_unshare+0x440/0x980 kernel/fork.c:2692
__do_sys_unshare kernel/fork.c:2760 [inline]
__se_sys_unshare kernel/fork.c:2758 [inline]
__x64_sys_unshare+0x31/0x40 kernel/fork.c:2758
do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
entry_SYSCALL_64_after_hwframe+0x49/0xbe
Freed by task 7:
save_stack+0x23/0x90 mm/kasan/common.c:71
set_track mm/kasan/common.c:79 [inline]
__kasan_slab_free+0x102/0x150 mm/kasan/common.c:451
kasan_slab_free+0xe/0x10 mm/kasan/common.c:459
__cache_free mm/slab.c:3432 [inline]
kfree+0xcf/0x220 mm/slab.c:3755
kvfree+0x61/0x70 mm/util.c:460
bucket_table_free+0x69/0x150 lib/rhashtable.c:108
rhashtable_free_and_destroy+0x165/0x8b0 lib/rhashtable.c:1155
inet_frags_exit_net+0x3d/0x50 net/ipv4/inet_fragment.c:152
ipv4_frags_exit_net+0x73/0x90 net/ipv4/ip_fragment.c:695
ops_exit_list.isra.0+0xaa/0x150 net/core/net_namespace.c:154
cleanup_net+0x3fb/0x960 net/core/net_namespace.c:553
process_one_work+0x989/0x1790 kernel/workqueue.c:2269
worker_thread+0x98/0xe40 kernel/workqueue.c:2415
kthread+0x354/0x420 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
The buggy address belongs to the object at ffff8880a6497b40
which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 48 bytes inside of
1024-byte region [ffff8880a6497b40, ffff8880a6497f40)
The buggy address belongs to the page:
page:ffffea0002992580 refcount:1 mapcount:0 mapping:ffff8880aa400ac0 index:0xffff8880a64964c0 compound_mapcount: 0
flags: 0x1fffc0000010200(slab|head)
raw: 01fffc0000010200 ffffea0002916e88 ffffea000218fe08 ffff8880aa400ac0
raw: ffff8880a64964c0 ffff8880a6496040 0000000100000005 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff8880a6497a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880a6497a80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff8880a6497b00: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
^
ffff8880a6497b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880a6497c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
Fixes:
|
||
|---|---|---|
| .. | ||
| 9p | ||
| bluetooth | ||
| caif | ||
| iucv | ||
| netfilter | ||
| netns | ||
| nfc | ||
| phonet | ||
| sctp | ||
| tc_act | ||
| 6lowpan.h | ||
| act_api.h | ||
| addrconf.h | ||
| af_ieee802154.h | ||
| af_rxrpc.h | ||
| af_unix.h | ||
| af_vsock.h | ||
| ah.h | ||
| arp.h | ||
| atmclip.h | ||
| ax25.h | ||
| ax88796.h | ||
| bond_3ad.h | ||
| bond_alb.h | ||
| bond_options.h | ||
| bonding.h | ||
| bpf_sk_storage.h | ||
| busy_poll.h | ||
| calipso.h | ||
| cfg80211-wext.h | ||
| cfg80211.h | ||
| cfg802154.h | ||
| checksum.h | ||
| cipso_ipv4.h | ||
| cls_cgroup.h | ||
| codel_impl.h | ||
| codel_qdisc.h | ||
| codel.h | ||
| compat.h | ||
| datalink.h | ||
| dcbevent.h | ||
| dcbnl.h | ||
| devlink.h | ||
| dn_dev.h | ||
| dn_fib.h | ||
| dn_neigh.h | ||
| dn_nsp.h | ||
| dn_route.h | ||
| dn.h | ||
| dsa.h | ||
| dsfield.h | ||
| dst_cache.h | ||
| dst_metadata.h | ||
| dst_ops.h | ||
| dst.h | ||
| erspan.h | ||
| esp.h | ||
| ethoc.h | ||
| failover.h | ||
| fib_notifier.h | ||
| fib_rules.h | ||
| firewire.h | ||
| flow_dissector.h | ||
| flow_offload.h | ||
| flow.h | ||
| fou.h | ||
| fq_impl.h | ||
| fq.h | ||
| garp.h | ||
| gen_stats.h | ||
| genetlink.h | ||
| geneve.h | ||
| gre.h | ||
| gro_cells.h | ||
| gtp.h | ||
| gue.h | ||
| hwbm.h | ||
| icmp.h | ||
| ieee80211_radiotap.h | ||
| ieee802154_netdev.h | ||
| if_inet6.h | ||
| ife.h | ||
| ila.h | ||
| inet6_connection_sock.h | ||
| inet6_hashtables.h | ||
| inet_common.h | ||
| inet_connection_sock.h | ||
| inet_ecn.h | ||
| inet_frag.h | ||
| inet_hashtables.h | ||
| inet_sock.h | ||
| inet_timewait_sock.h | ||
| inetpeer.h | ||
| ip6_checksum.h | ||
| ip6_fib.h | ||
| ip6_route.h | ||
| ip6_tunnel.h | ||
| ip_fib.h | ||
| ip_tunnels.h | ||
| ip_vs.h | ||
| ip.h | ||
| ipcomp.h | ||
| ipconfig.h | ||
| ipv6_frag.h | ||
| ipv6_stubs.h | ||
| ipv6.h | ||
| ipx.h | ||
| iw_handler.h | ||
| kcm.h | ||
| l3mdev.h | ||
| lag.h | ||
| lapb.h | ||
| lib80211.h | ||
| llc_c_ac.h | ||
| llc_c_ev.h | ||
| llc_c_st.h | ||
| llc_conn.h | ||
| llc_if.h | ||
| llc_pdu.h | ||
| llc_s_ac.h | ||
| llc_s_ev.h | ||
| llc_s_st.h | ||
| llc_sap.h | ||
| llc.h | ||
| lwtunnel.h | ||
| mac80211.h | ||
| mac802154.h | ||
| mip6.h | ||
| mld.h | ||
| mpls_iptunnel.h | ||
| mpls.h | ||
| mrp.h | ||
| ncsi.h | ||
| ndisc.h | ||
| neighbour.h | ||
| net_failover.h | ||
| net_namespace.h | ||
| net_ratelimit.h | ||
| netevent.h | ||
| netlabel.h | ||
| netlink.h | ||
| netprio_cgroup.h | ||
| netrom.h | ||
| nl802154.h | ||
| nsh.h | ||
| p8022.h | ||
| page_pool.h | ||
| ping.h | ||
| pkt_cls.h | ||
| pkt_sched.h | ||
| pptp.h | ||
| protocol.h | ||
| psample.h | ||
| psnap.h | ||
| raw.h | ||
| rawv6.h | ||
| red.h | ||
| regulatory.h | ||
| request_sock.h | ||
| rose.h | ||
| route.h | ||
| rsi_91x.h | ||
| rtnetlink.h | ||
| rtnh.h | ||
| sch_generic.h | ||
| scm.h | ||
| secure_seq.h | ||
| seg6_hmac.h | ||
| seg6_local.h | ||
| seg6.h | ||
| slhc_vj.h | ||
| smc.h | ||
| snmp.h | ||
| sock_reuseport.h | ||
| sock.h | ||
| Space.h | ||
| stp.h | ||
| strparser.h | ||
| switchdev.h | ||
| tcp_states.h | ||
| tcp.h | ||
| timewait_sock.h | ||
| tipc.h | ||
| tls.h | ||
| transp_v6.h | ||
| tso.h | ||
| tun_proto.h | ||
| udp_tunnel.h | ||
| udp.h | ||
| udplite.h | ||
| vsock_addr.h | ||
| vxlan.h | ||
| wext.h | ||
| wimax.h | ||
| x25.h | ||
| x25device.h | ||
| xdp_sock.h | ||
| xdp.h | ||
| xfrm.h | ||