diff options
| author | David Howells <dhowells@redhat.com> | 2022-08-16 10:34:40 +0100 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2022-08-17 16:42:59 -0700 |
| commit | fc4aaf9fb3c99bcb326d52f9d320ed5680bd1cee (patch) | |
| tree | 47a4384fbc5b072ebf68799b4c80604bc907245c /kernel | |
| parent | 36c0d935015766bf20d621c18313f17691bda5e3 (diff) | |
net: Fix suspicious RCU usage in bpf_sk_reuseport_detach()
bpf_sk_reuseport_detach() calls __rcu_dereference_sk_user_data_with_flags()
to obtain the value of sk->sk_user_data, but that function is only usable
if the RCU read lock is held, and neither that function nor any of its
callers hold it.
Fix this by adding a new helper, __locked_read_sk_user_data_with_flags()
that checks to see if sk->sk_callback_lock() is held and use that here
instead.
Alternatively, making __rcu_dereference_sk_user_data_with_flags() use
rcu_dereference_checked() might suffice.
Without this, the following warning can be occasionally observed:
=============================
WARNING: suspicious RCU usage
6.0.0-rc1-build2+ #563 Not tainted
-----------------------------
include/net/sock.h:592 suspicious rcu_dereference_check() usage!
other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 1
5 locks held by locktest/29873:
#0: ffff88812734b550 (&sb->s_type->i_mutex_key#9){+.+.}-{3:3}, at: __sock_release+0x77/0x121
#1: ffff88812f5621b0 (sk_lock-AF_INET){+.+.}-{0:0}, at: tcp_close+0x1c/0x70
#2: ffff88810312f5c8 (&h->lhash2[i].lock){+.+.}-{2:2}, at: inet_unhash+0x76/0x1c0
#3: ffffffff83768bb8 (reuseport_lock){+...}-{2:2}, at: reuseport_detach_sock+0x18/0xdd
#4: ffff88812f562438 (clock-AF_INET){++..}-{2:2}, at: bpf_sk_reuseport_detach+0x24/0xa4
stack backtrace:
CPU: 1 PID: 29873 Comm: locktest Not tainted 6.0.0-rc1-build2+ #563
Hardware name: ASUS All Series/H97-PLUS, BIOS 2306 10/09/2014
Call Trace:
<TASK>
dump_stack_lvl+0x4c/0x5f
bpf_sk_reuseport_detach+0x6d/0xa4
reuseport_detach_sock+0x75/0xdd
inet_unhash+0xa5/0x1c0
tcp_set_state+0x169/0x20f
? lockdep_sock_is_held+0x3a/0x3a
? __lock_release.isra.0+0x13e/0x220
? reacquire_held_locks+0x1bb/0x1bb
? hlock_class+0x31/0x96
? mark_lock+0x9e/0x1af
__tcp_close+0x50/0x4b6
tcp_close+0x28/0x70
inet_release+0x8e/0xa7
__sock_release+0x95/0x121
sock_close+0x14/0x17
__fput+0x20f/0x36a
task_work_run+0xa3/0xcc
exit_to_user_mode_prepare+0x9c/0x14d
syscall_exit_to_user_mode+0x18/0x44
entry_SYSCALL_64_after_hwframe+0x63/0xcd
Fixes: cf8c1e967224 ("net: refactor bpf_sk_reuseport_detach()")
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Hawkins Jiawei <yin31149@gmail.com>
Link: https://lore.kernel.org/r/166064248071.3502205.10036394558814861778.stgit@warthog.procyon.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/reuseport_array.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/bpf/reuseport_array.c b/kernel/bpf/reuseport_array.c index 85fa9dbfa8bf..82c61612f382 100644 --- a/kernel/bpf/reuseport_array.c +++ b/kernel/bpf/reuseport_array.c @@ -24,7 +24,7 @@ void bpf_sk_reuseport_detach(struct sock *sk) struct sock __rcu **socks; write_lock_bh(&sk->sk_callback_lock); - socks = __rcu_dereference_sk_user_data_with_flags(sk, SK_USER_DATA_BPF); + socks = __locked_read_sk_user_data_with_flags(sk, SK_USER_DATA_BPF); if (socks) { WRITE_ONCE(sk->sk_user_data, NULL); /* |