Merge branch 'net-tls-Annotate-lockless-access-to-sk_prot'

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Jakub Sitnicki says:

====================
net/tls: Annotate lockless access to sk_prot

We have recently noticed that there is a case of lockless read/write to
sk->sk_prot [0]. sockmap code on psock tear-down writes to sk->sk_prot,
while holding sk_callback_lock. Concurrently, tcp can access it. Usually to
read out the sk_prot pointer and invoke one of the ops,
sk->sk_prot->handler().

The lockless write (lockless in regard to concurrent reads) happens on the
following paths:

tcp_bpf_{recvmsg|sendmsg} / sock_map_unref
  sk_psock_put
    sk_psock_drop
      sk_psock_restore_proto
        WRITE_ONCE(sk->sk_prot, proto)

To prevent load/store tearing [1], and to make tooling aware of intentional
shared access [2], we need to annotate sites that access sk_prot with
READ_ONCE/WRITE_ONCE.

This series kicks off the effort to do it. Starting with net/tls.

[0] https://lore.kernel.org/bpf/a6bf279e-a998-84ab-4371-cd6c1ccbca5d@gmail.com/
[1] https://lwn.net/Articles/793253/
[2] https://github.com/google/ktsan/wiki/READ_ONCE-and-WRITE_ONCE
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

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This commit is contained in:

David S. Miller 2020-03-21 20:08:17 -07:00

parent 26922c0ef3 d5bee7374b

commit e28596012d

2 changed files with 16 additions and 14 deletions

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net/tls/tls_device.c

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28

net/tls/tls_main.c

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