kernel/linux.git/net/rds/tcp.c, branch linux-4.16.y

rds: tcp: must use spin_lock_irq* and not spin_lock_bh with rds_tcp_conn_lock

2018-05-16T08:12:25+00:00

commit 53d0e83f9329aa51dcc205b514dbee05cb4df309 upstream. rds_tcp_connection allocation/free management has the potential to be called from __rds_conn_create after IRQs have been disabled, so spin_[un]lock_bh cannot be used with rds_tcp_conn_lock. Bottom-halves that need to synchronize for critical sections protected by rds_tcp_conn_lock should instead use rds_destroy_pending() correctly. Reported-by: syzbot+c68e51bb5e699d3f8d91@syzkaller.appspotmail.com Fixes: ebeeb1ad9b8a ("rds: tcp: use rds_destroy_pending() to synchronize netns/module teardown and rds connection/workq management") Signed-off-by: Sowmini Varadhan Acked-by: Santosh Shilimkar Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

rds: tcp: use rds_destroy_pending() to synchronize netns/module teardown and rds connection/workq management

2018-02-08T20:23:52+00:00

An rds_connection can get added during netns deletion between lines 528 and 529 of 506 static void rds_tcp_kill_sock(struct net *net) : /* code to pull out all the rds_connections that should be destroyed */ : 528 spin_unlock_irq(&rds_tcp_conn_lock); 529 list_for_each_entry_safe(tc, _tc, &tmp_list, t_tcp_node) 530 rds_conn_destroy(tc->t_cpath->cp_conn); Such an rds_connection would miss out the rds_conn_destroy() loop (that cancels all pending work) and (if it was scheduled after netns deletion) could trigger the use-after-free. A similar race-window exists for the module unload path in rds_tcp_exit -> rds_tcp_destroy_conns Concurrency with netns deletion (rds_tcp_kill_sock()) must be handled by checking check_net() before enqueuing new work or adding new connections. Concurrency with module-unload is handled by maintaining a module specific flag that is set at the start of the module exit function, and must be checked before enqueuing new work or adding new connections. This commit refactors existing RDS_DESTROY_PENDING checks added by commit 3db6e0d172c9 ("rds: use RCU to synchronize work-enqueue with connection teardown") and consolidates all the concurrency checks listed above into the function rds_destroy_pending(). Signed-off-by: Sowmini Varadhan Acked-by: Santosh Shilimkar Signed-off-by: David S. Miller

Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net

2018-01-23T18:51:56+00:00

en_rx_am.c was deleted in 'net-next' but had a bug fixed in it in 'net'. The esp{4,6}_offload.c conflicts were overlapping changes. The 'out' label is removed so we just return ERR_PTR(-EINVAL) directly. Signed-off-by: David S. Miller

rds: tcp: compute m_ack_seq as offset from ->write_seq

2018-01-22T20:43:54+00:00

rds-tcp uses m_ack_seq to track the tcp ack# that indicates that the peer has received a rds_message. The m_ack_seq is used in rds_tcp_is_acked() to figure out when it is safe to drop the rds_message from the RDS retransmit queue. The m_ack_seq must be calculated as an offset from the right edge of the in-flight tcp buffer, i.e., it should be based on the ->write_seq, not the ->snd_nxt. Signed-off-by: Sowmini Varadhan Signed-off-by: David S. Miller

rds: tcp: cleanup if kmem_cache_alloc fails in rds_tcp_conn_alloc()

2017-12-27T18:37:27+00:00

If kmem_cache_alloc() fails in the middle of the for() loop, cleanup anything that might have been allocated so far. Signed-off-by: Sowmini Varadhan Acked-by: Santosh Shilimkar Signed-off-by: David S. Miller

rds: tcp: initialize t_tcp_detached to false

2017-12-27T18:37:27+00:00

Commit f10b4cff98c6 ("rds: tcp: atomically purge entries from rds_tcp_conn_list during netns delete") adds the field t_tcp_detached, but this needs to be initialized explicitly to false. Signed-off-by: Sowmini Varadhan Acked-by: Santosh Shilimkar Signed-off-by: David S. Miller

rds: tcp: atomically purge entries from rds_tcp_conn_list during netns delete

2017-12-01T20:25:15+00:00

The rds_tcp_kill_sock() function parses the rds_tcp_conn_list to find the rds_connection entries marked for deletion as part of the netns deletion under the protection of the rds_tcp_conn_lock. Since the rds_tcp_conn_list tracks rds_tcp_connections (which have a 1:1 mapping with rds_conn_path), multiple tc entries in the rds_tcp_conn_list will map to a single rds_connection, and will be deleted as part of the rds_conn_destroy() operation that is done outside the rds_tcp_conn_lock. The rds_tcp_conn_list traversal done under the protection of rds_tcp_conn_lock should not leave any doomed tc entries in the list after the rds_tcp_conn_lock is released, else another concurrently executiong netns delete (for a differnt netns) thread may trip on these entries. Reported-by: syzbot Signed-off-by: Sowmini Varadhan Acked-by: Santosh Shilimkar Signed-off-by: David S. Miller

rds: tcp: correctly sequence cleanup on netns deletion.

2017-12-01T20:25:15+00:00

Commit 8edc3affc077 ("rds: tcp: Take explicit refcounts on struct net") introduces a regression in rds-tcp netns cleanup. The cleanup_net(), (and thus rds_tcp_dev_event notification) is only called from put_net() when all netns refcounts go to 0, but this cannot happen if the rds_connection itself is holding a c_net ref that it expects to release in rds_tcp_kill_sock. Instead, the rds_tcp_kill_sock callback should make sure to tear down state carefully, ensuring that the socket teardown is only done after all data-structures and workqs that depend on it are quiesced. The original motivation for commit 8edc3affc077 ("rds: tcp: Take explicit refcounts on struct net") was to resolve a race condition reported by syzkaller where workqs for tx/rx/connect were triggered after the namespace was deleted. Those worker threads should have been cancelled/flushed before socket tear-down and indeed, rds_conn_path_destroy() does try to sequence this by doing /* cancel cp_send_w */ /* cancel cp_recv_w */ /* flush cp_down_w */ /* free data structures */ Here the "flush cp_down_w" will trigger rds_conn_shutdown and thus invoke rds_tcp_conn_path_shutdown() to close the tcp socket, so that we ought to have satisfied the requirement that "socket-close is done after all other dependent state is quiesced". However, rds_conn_shutdown has a bug in that it *always* triggers the reconnect workq (and if connection is successful, we always restart tx/rx workqs so with the right timing, we risk the race conditions reported by syzkaller). Netns deletion is like module teardown- no need to restart a reconnect in this case. We can use the c_destroy_in_prog bit to avoid restarting the reconnect. Fixes: 8edc3affc077 ("rds: tcp: Take explicit refcounts on struct net") Signed-off-by: Sowmini Varadhan Acked-by: Santosh Shilimkar Signed-off-by: David S. Miller

rds: tcp: remove redundant function rds_tcp_conn_paths_destroy()

2017-12-01T20:25:15+00:00

A side-effect of Commit c14b0366813a ("rds: tcp: set linger to 1 when unloading a rds-tcp") is that we always send a RST on the tcp connection for rds_conn_destroy(), so rds_tcp_conn_paths_destroy() is not needed any more and is removed in this patch. Signed-off-by: Sowmini Varadhan Acked-by: Santosh Shilimkar Signed-off-by: David S. Miller

rds: cancel send/recv work before queuing connection shutdown

2017-07-17T02:07:35+00:00

We could end up executing rds_conn_shutdown before the rds_recv_worker thread, then rds_conn_shutdown -> rds_tcp_conn_shutdown can do a sock_release and set sock->sk to null, which may interleave in bad ways with rds_recv_worker, e.g., it could result in: "BUG: unable to handle kernel NULL pointer dereference at 0000000000000078" [ffff881769f6fd70] release_sock at ffffffff815f337b [ffff881769f6fd90] rds_tcp_recv at ffffffffa043c888 [rds_tcp] [ffff881769f6fdb0] rds_recv_worker at ffffffffa04a4810 [rds] [ffff881769f6fde0] process_one_work at ffffffff810a14c1 [ffff881769f6fe40] worker_thread at ffffffff810a1940 [ffff881769f6fec0] kthread at ffffffff810a6b1e Also, do not enqueue any new shutdown workq items when the connection is shutting down (this may happen for rds-tcp in softirq mode, if a FIN or CLOSE is received while the modules is in the middle of an unload) Signed-off-by: Sowmini Varadhan Signed-off-by: David S. Miller