Jakub Sitnicki 75e68e5bf2 bpf, sockhash: Synchronize delete from bucket list on map free ... We can end up modifying the sockhash bucket list from two CPUs when a sockhash is being destroyed (sock_hash_free) on one CPU, while a socket that is in the sockhash is unlinking itself from it on another CPU it (sock_hash_delete_from_link). This results in accessing a list element that is in an undefined state as reported by KASAN: | ================================================================== | BUG: KASAN: wild-memory-access in sock_hash_free+0x13c/0x280 | Write of size 8 at addr dead000000000122 by task kworker/2:1/95 | | CPU: 2 PID: 95 Comm: kworker/2:1 Not tainted 5.7.0-rc7-02961-ge22c35ab0038-dirty #691 | Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_073836-buildvm-ppc64le-16.ppc.fedoraproject.org-3.fc31 04/01/2014 | Workqueue: events bpf_map_free_deferred | Call Trace: | dump_stack+0x97/0xe0 | ? sock_hash_free+0x13c/0x280 | __kasan_report.cold+0x5/0x40 | ? mark_lock+0xbc1/0xc00 | ? sock_hash_free+0x13c/0x280 | kasan_report+0x38/0x50 | ? sock_hash_free+0x152/0x280 | sock_hash_free+0x13c/0x280 | bpf_map_free_deferred+0xb2/0xd0 | ? bpf_map_charge_finish+0x50/0x50 | ? rcu_read_lock_sched_held+0x81/0xb0 | ? rcu_read_lock_bh_held+0x90/0x90 | process_one_work+0x59a/0xac0 | ? lock_release+0x3b0/0x3b0 | ? pwq_dec_nr_in_flight+0x110/0x110 | ? rwlock_bug.part.0+0x60/0x60 | worker_thread+0x7a/0x680 | ? _raw_spin_unlock_irqrestore+0x4c/0x60 | kthread+0x1cc/0x220 | ? process_one_work+0xac0/0xac0 | ? kthread_create_on_node+0xa0/0xa0 | ret_from_fork+0x24/0x30 | ================================================================== Fix it by reintroducing spin-lock protected critical section around the code that removes the elements from the bucket on sockhash free. To do that we also need to defer processing of removed elements, until out of atomic context so that we can unlink the socket from the map when holding the sock lock. Fixes: 90db6d772f ("bpf, sockmap: Remove bucket->lock from sock_{hash|map}_free") Reported-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: John Fastabend <john.fastabend@gmail.com> Link: https://lore.kernel.org/bpf/20200607205229.2389672-3-jakub@cloudflare.com		2020-06-09 10:59:04 -07:00
..
6lowpan
9p
802
8021q
appletalk
atm
ax25
batman-adv
bluetooth
bpf
bpfilter
bridge
caif
can
ceph
core	bpf, sockhash: Synchronize delete from bucket list on map free	2020-06-09 10:59:04 -07:00
dcb
dccp
decnet
dns_resolver
dsa
ethernet
ethtool
hsr
ieee802154
ife
ipv4	bpf/sockmap: Fix kernel panic at __tcp_bpf_recvmsg	2020-06-09 10:56:36 -07:00
ipv6
iucv
kcm
key
l2tp
l3mdev
lapb
llc
mac80211
mac802154
mpls
mptcp
ncsi
netfilter
netlabel
netlink
netrom
nfc
nsh
openvswitch
packet
phonet
psample
qrtr
rds
rfkill
rose
rxrpc
sched
sctp
smc
strparser
sunrpc
switchdev
tipc
tls
unix
vmw_vsock
wimax
wireless
x25
xdp
xfrm
compat.c
devres.c
Kconfig
Makefile
socket.c
sysctl_net.c