diff options
| author | Eric Dumazet <edumazet@google.com> | 2018-10-02 22:35:05 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-10-18 10:16:21 +0300 |
| commit | c5df58138946fe24d3cb0c99bb6ce04130c657b7 (patch) | |
| tree | 6c594a596d34cc485da5b2084712e64e0bd40fd2 /net/ipv4/tcp_ipv4.c | |
| parent | 17af5475aef350b78875646b2795381f452de756 (diff) | |
| download | linux-c5df58138946fe24d3cb0c99bb6ce04130c657b7.tar.xz | |
inet: make sure to grab rcu_read_lock before using ireq->ireq_opt
[ Upstream commit 2ab2ddd301a22ca3c5f0b743593e4ad2953dfa53 ]
Timer handlers do not imply rcu_read_lock(), so my recent fix
triggered a LOCKDEP warning when SYNACK is retransmit.
Lets add rcu_read_lock()/rcu_read_unlock() pairs around ireq->ireq_opt
usages instead of guessing what is done by callers, since it is
not worth the pain.
Get rid of ireq_opt_deref() helper since it hides the logic
without real benefit, since it is now a standard rcu_dereference().
Fixes: 1ad98e9d1bdf ("tcp/dccp: fix lockdep issue when SYN is backlogged")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net/ipv4/tcp_ipv4.c')
| -rw-r--r-- | net/ipv4/tcp_ipv4.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 0e1a670dabd9..31b34c0c2d5f 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -875,9 +875,11 @@ static int tcp_v4_send_synack(const struct sock *sk, struct dst_entry *dst, if (skb) { __tcp_v4_send_check(skb, ireq->ir_loc_addr, ireq->ir_rmt_addr); + rcu_read_lock(); err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr, ireq->ir_rmt_addr, - ireq_opt_deref(ireq)); + rcu_dereference(ireq->ireq_opt)); + rcu_read_unlock(); err = net_xmit_eval(err); } |