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51d1b25a72
syzkaller reported data-race of sk->sk_hash in unix_autobind() [0],
and the same ones exist in unix_bind_bsd() and unix_bind_abstract().
The three bind() functions prefetch sk->sk_hash locklessly and
use it later after validating that unix_sk(sk)->addr is NULL under
unix_sk(sk)->bindlock.
The prefetched sk->sk_hash is the hash value of unbound socket set
in unix_create1() and does not change until bind() completes.
There could be a chance that sk->sk_hash changes after the lockless
read. However, in such a case, non-NULL unix_sk(sk)->addr is visible
under unix_sk(sk)->bindlock, and bind() returns -EINVAL without using
the prefetched value.
The KCSAN splat is false-positive, but let's silence it by reading
sk->sk_hash under unix_sk(sk)->bindlock.
[0]:
BUG: KCSAN: data-race in unix_autobind / unix_autobind
write to 0xffff888034a9fb88 of 4 bytes by task 4468 on cpu 0:
__unix_set_addr_hash net/unix/af_unix.c:331 [inline]
unix_autobind+0x47a/0x7d0 net/unix/af_unix.c:1185
unix_dgram_connect+0x7e3/0x890 net/unix/af_unix.c:1373
__sys_connect_file+0xd7/0xe0 net/socket.c:2048
__sys_connect+0x114/0x140 net/socket.c:2065
__do_sys_connect net/socket.c:2075 [inline]
__se_sys_connect net/socket.c:2072 [inline]
__x64_sys_connect+0x40/0x50 net/socket.c:2072
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0x4f/0x110 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x46/0x4e
read to 0xffff888034a9fb88 of 4 bytes by task 4465 on cpu 1:
unix_autobind+0x28/0x7d0 net/unix/af_unix.c:1134
unix_dgram_connect+0x7e3/0x890 net/unix/af_unix.c:1373
__sys_connect_file+0xd7/0xe0 net/socket.c:2048
__sys_connect+0x114/0x140 net/socket.c:2065
__do_sys_connect net/socket.c:2075 [inline]
__se_sys_connect net/socket.c:2072 [inline]
__x64_sys_connect+0x40/0x50 net/socket.c:2072
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0x4f/0x110 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x46/0x4e
value changed: 0x000000e4 -> 0x000001e3
Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 4465 Comm: syz-executor.0 Not tainted 6.8.0-12822-gcd51db110a7e #12
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
Fixes:
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.. | ||
6lowpan | ||
9p | ||
802 | ||
8021q | ||
appletalk | ||
atm | ||
ax25 | ||
batman-adv | ||
bluetooth | ||
bpf | ||
bridge | ||
caif | ||
can | ||
ceph | ||
core | ||
dcb | ||
dccp | ||
devlink | ||
dns_resolver | ||
dsa | ||
ethernet | ||
ethtool | ||
handshake | ||
hsr | ||
ieee802154 | ||
ife | ||
ipv4 | ||
ipv6 | ||
iucv | ||
kcm | ||
key | ||
l2tp | ||
l3mdev | ||
lapb | ||
llc | ||
mac80211 | ||
mac802154 | ||
mctp | ||
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 | ||
wireless | ||
x25 | ||
xdp | ||
xfrm | ||
compat.c | ||
devres.c | ||
Kconfig | ||
Kconfig.debug | ||
Makefile | ||
socket.c | ||
sysctl_net.c |