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| author | Qian Cai <cai@lca.pw> | 2020-02-04 13:40:29 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-10-01 13:14:32 +0200 |
| commit | 1fea0234984c39748386a8b2eebaf8a1561e3075 (patch) | |
| tree | b7038d9f990ca66a6e4ab259b5b5c3738043dad6 /net/unix | |
| parent | 63cf8e58c21322bd57357fcb7ff19c3d7ef89b97 (diff) | |
| download | linux-stable-1fea0234984c39748386a8b2eebaf8a1561e3075.tar.gz linux-stable-1fea0234984c39748386a8b2eebaf8a1561e3075.tar.bz2 linux-stable-1fea0234984c39748386a8b2eebaf8a1561e3075.zip | |
skbuff: fix a data race in skb_queue_len()
[ Upstream commit 86b18aaa2b5b5bb48e609cd591b3d2d0fdbe0442 ]
sk_buff.qlen can be accessed concurrently as noticed by KCSAN,
BUG: KCSAN: data-race in __skb_try_recv_from_queue / unix_dgram_sendmsg
read to 0xffff8a1b1d8a81c0 of 4 bytes by task 5371 on cpu 96:
unix_dgram_sendmsg+0x9a9/0xb70 include/linux/skbuff.h:1821
net/unix/af_unix.c:1761
____sys_sendmsg+0x33e/0x370
___sys_sendmsg+0xa6/0xf0
__sys_sendmsg+0x69/0xf0
__x64_sys_sendmsg+0x51/0x70
do_syscall_64+0x91/0xb47
entry_SYSCALL_64_after_hwframe+0x49/0xbe
write to 0xffff8a1b1d8a81c0 of 4 bytes by task 1 on cpu 99:
__skb_try_recv_from_queue+0x327/0x410 include/linux/skbuff.h:2029
__skb_try_recv_datagram+0xbe/0x220
unix_dgram_recvmsg+0xee/0x850
____sys_recvmsg+0x1fb/0x210
___sys_recvmsg+0xa2/0xf0
__sys_recvmsg+0x66/0xf0
__x64_sys_recvmsg+0x51/0x70
do_syscall_64+0x91/0xb47
entry_SYSCALL_64_after_hwframe+0x49/0xbe
Since only the read is operating as lockless, it could introduce a logic
bug in unix_recvq_full() due to the load tearing. Fix it by adding
a lockless variant of skb_queue_len() and unix_recvq_full() where
READ_ONCE() is on the read while WRITE_ONCE() is on the write similar to
the commit d7d16a89350a ("net: add skb_queue_empty_lockless()").
Signed-off-by: Qian Cai <cai@lca.pw>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'net/unix')
| -rw-r--r-- | net/unix/af_unix.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 2318e2e2748f..2020306468af 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -192,11 +192,17 @@ static inline int unix_may_send(struct sock *sk, struct sock *osk) return unix_peer(osk) == NULL || unix_our_peer(sk, osk); } -static inline int unix_recvq_full(struct sock const *sk) +static inline int unix_recvq_full(const struct sock *sk) { return skb_queue_len(&sk->sk_receive_queue) > sk->sk_max_ack_backlog; } +static inline int unix_recvq_full_lockless(const struct sock *sk) +{ + return skb_queue_len_lockless(&sk->sk_receive_queue) > + READ_ONCE(sk->sk_max_ack_backlog); +} + struct sock *unix_peer_get(struct sock *s) { struct sock *peer; @@ -1788,7 +1794,8 @@ restart_locked: * - unix_peer(sk) == sk by time of get but disconnected before lock */ if (other != sk && - unlikely(unix_peer(other) != sk && unix_recvq_full(other))) { + unlikely(unix_peer(other) != sk && + unix_recvq_full_lockless(other))) { if (timeo) { timeo = unix_wait_for_peer(other, timeo); |