linux/net/dccp
Eric Dumazet 5e0724d027 tcp/dccp: fix hashdance race for passive sessions
Multiple cpus can process duplicates of incoming ACK messages
matching a SYN_RECV request socket. This is a rare event under
normal operations, but definitely can happen.

Only one must win the race, otherwise corruption would occur.

To fix this without adding new atomic ops, we use logic in
inet_ehash_nolisten() to detect the request was present in the same
ehash bucket where we try to insert the new child.

If request socket was not found, we have to undo the child creation.

This actually removes a spin_lock()/spin_unlock() pair in
reqsk_queue_unlink() for the fast path.

Fixes: e994b2f0fb ("tcp: do not lock listener to process SYN packets")
Fixes: 079096f103 ("tcp/dccp: install syn_recv requests into ehash table")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-10-23 05:42:21 -07:00
..
ccids dccp: re-enable debug macro 2014-02-16 23:45:00 -05:00
ackvec.c dccp: drop null test before destroy functions 2015-09-15 16:49:43 -07:00
ackvec.h net: dccp: Remove extern from function prototypes 2013-10-19 19:12:11 -04:00
ccid.c dccp: drop null test before destroy functions 2015-09-15 16:49:43 -07:00
ccid.h net: dccp: Remove extern from function prototypes 2013-10-19 19:12:11 -04:00
dccp.h tcp/dccp: fix hashdance race for passive sessions 2015-10-23 05:42:21 -07:00
diag.c sock_diag: specify info_size per inet protocol 2015-06-15 19:49:22 -07:00
feat.c dccp: kerneldoc warning fixes 2014-11-18 15:26:31 -05:00
feat.h net: dccp: Remove extern from function prototypes 2013-10-19 19:12:11 -04:00
input.c dccp: spelling s/reseting/resetting 2014-11-18 15:26:32 -05:00
ipv4.c tcp/dccp: fix hashdance race for passive sessions 2015-10-23 05:42:21 -07:00
ipv6.c tcp/dccp: fix hashdance race for passive sessions 2015-10-23 05:42:21 -07:00
ipv6.h inet: includes a sock_common in request_sock 2013-10-10 00:08:07 -04:00
Kconfig net/dccp: remove depends on CONFIG_EXPERIMENTAL 2013-01-11 11:39:34 -08:00
Makefile
minisocks.c tcp/dccp: fix hashdance race for passive sessions 2015-10-23 05:42:21 -07:00
options.c dccp: remove obsolete code 2014-01-04 20:18:49 -05:00
output.c dccp: constify dccp_make_response() socket argument 2015-09-25 13:00:39 -07:00
probe.c net: Remove iocb argument from sendmsg and recvmsg 2015-03-02 13:06:31 -05:00
proto.c tcp: fix recv with flags MSG_WAITALL | MSG_PEEK 2015-07-27 01:06:53 -07:00
qpolicy.c
sysctl.c dccp: make the request_retries minimum is 1 2014-05-14 15:34:16 -04:00
timer.c inet: get rid of central tcp/dccp listener timer 2015-03-20 12:40:25 -04:00