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| author | Sowmini Varadhan <sowmini.varadhan@oracle.com> | 2016-05-02 21:24:51 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-05-03 23:03:44 +0300 |
| commit | eb192840266fab3e3da644018121eed30153355d (patch) | |
| tree | 882f8ee60fe758e2e78275cdf00349cce1878000 /net/rds/tcp.c | |
| parent | 42c8819b8d7245f54d5cfa6c2ec5a436818aeda9 (diff) | |
| download | linux-eb192840266fab3e3da644018121eed30153355d.tar.xz | |
RDS:TCP: Synchronize rds_tcp_accept_one with rds_send_xmit when resetting t_sock
There is a race condition between rds_send_xmit -> rds_tcp_xmit
and the code that deals with resolution of duelling syns added
by commit 241b271952eb ("RDS-TCP: Reset tcp callbacks if re-using an
outgoing socket in rds_tcp_accept_one()").
Specifically, we may end up derefencing a null pointer in rds_send_xmit
if we have the interleaving sequence:
rds_tcp_accept_one rds_send_xmit
conn is RDS_CONN_UP, so
invoke rds_tcp_xmit
tc = conn->c_transport_data
rds_tcp_restore_callbacks
/* reset t_sock */
null ptr deref from tc->t_sock
The race condition can be avoided without adding the overhead of
additional locking in the xmit path: have rds_tcp_accept_one wait
for rds_tcp_xmit threads to complete before resetting callbacks.
The synchronization can be done in the same manner as rds_conn_shutdown().
First set the rds_conn_state to something other than RDS_CONN_UP
(so that new threads cannot get into rds_tcp_xmit()), then wait for
RDS_IN_XMIT to be cleared in the conn->c_flags indicating that any
threads in rds_tcp_xmit are done.
Fixes: 241b271952eb ("RDS-TCP: Reset tcp callbacks if re-using an
outgoing socket in rds_tcp_accept_one()")
Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/rds/tcp.c')
| -rw-r--r-- | net/rds/tcp.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/rds/tcp.c b/net/rds/tcp.c index 61ed2a8764ba..9134544941c2 100644 --- a/net/rds/tcp.c +++ b/net/rds/tcp.c @@ -127,7 +127,7 @@ void rds_tcp_restore_callbacks(struct socket *sock, /* * This is the only path that sets tc->t_sock. Send and receive trust that - * it is set. The RDS_CONN_CONNECTED bit protects those paths from being + * it is set. The RDS_CONN_UP bit protects those paths from being * called while it isn't set. */ void rds_tcp_set_callbacks(struct socket *sock, struct rds_connection *conn) |