linux/net/sctp
Neil Horman d9749fb594 sctp: Fix port hash table size computation
Dmitry Vyukov noted recently that the sctp_port_hashtable had an error in
its size computation, observing that the current method never guaranteed
that the hashsize (measured in number of entries) would be a power of two,
which the input hash function for that table requires.  The root cause of
the problem is that two values need to be computed (one, the allocation
order of the storage requries, as passed to __get_free_pages, and two the
number of entries for the hash table).  Both need to be ^2, but for
different reasons, and the existing code is simply computing one order
value, and using it as the basis for both, which is wrong (i.e. it assumes
that ((1<<order)*PAGE_SIZE)/sizeof(bucket) is still ^2 when its not).

To fix this, we change the logic slightly.  We start by computing a goal
allocation order (which is limited by the maximum size hash table we want
to support.  Then we attempt to allocate that size table, decreasing the
order until a successful allocation is made.  Then, with the resultant
successful order we compute the number of buckets that hash table supports,
which we then round down to the nearest power of two, giving us the number
of entries the table actually supports.

I've tested this locally here, using non-debug and spinlock-debug kernels,
and the number of entries in the hashtable consistently work out to be
powers of two in all cases.

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
CC: Dmitry Vyukov <dvyukov@google.com>
CC: Vladislav Yasevich <vyasevich@gmail.com>
CC: "David S. Miller" <davem@davemloft.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-02-21 21:52:51 -05:00
..
associola.c sctp: apply rhashtable api to send/recv path 2016-01-05 12:24:01 -05:00
auth.c sctp: translate host order to network order when setting a hmacid 2015-11-15 18:27:27 -05:00
bind_addr.c sctp: Fix FSF address in file headers 2013-12-06 12:37:56 -05:00
chunk.c switch sctp_user_addto_chunk() and sctp_datamsg_from_user() to passing iov_iter 2014-11-24 05:16:40 -05:00
debug.c sctp: Fix FSF address in file headers 2013-12-06 12:37:56 -05:00
endpointola.c sctp: the temp asoc's transports should not be hashed/unhashed 2016-01-17 19:11:44 -05:00
input.c sctp: fix the transport dead race check by using atomic_add_unless on refcnt 2016-01-28 15:59:32 -08:00
inqueue.c net: sctp: fix remote memory pressure from excessive queueing 2014-10-14 12:46:22 -04:00
ipv6.c ipv6: sctp: clone options to avoid use after free 2015-12-11 20:18:40 -05:00
Kconfig net: sctp: get rid of SCTP_DBG_TSNS entirely 2013-07-02 00:08:03 -07:00
Makefile net: sctp: Inline the functions from command.c 2014-07-08 14:38:48 -07:00
objcnt.c sctp: fix checkpatch errors with (foo*)|foo * bar|foo* bar 2013-12-26 13:47:47 -05:00
output.c sctp: Rename NETIF_F_SCTP_CSUM to NETIF_F_SCTP_CRC 2015-12-15 16:49:58 -05:00
outqueue.c sctp: start t5 timer only when peer rwnd is 0 and local state is SHUTDOWN_PENDING 2015-12-06 22:31:51 -05:00
primitive.c sctp: Fix FSF address in file headers 2013-12-06 12:37:56 -05:00
probe.c sctp: loading sctp when load sctp_probe 2013-12-16 20:04:27 -05:00
proc.c sctp: remove the dead field of sctp_transport 2016-01-28 15:59:32 -08:00
protocol.c sctp: Fix port hash table size computation 2016-02-21 21:52:51 -05:00
sm_make_chunk.c sctp: use the same clock as if sock source timestamps were on 2015-12-05 22:23:22 -05:00
sm_sideeffect.c sctp: remove the dead field of sctp_transport 2016-01-28 15:59:32 -08:00
sm_statefuns.c sctp: fix use-after-free in pr_debug statement 2016-01-11 17:13:01 -05:00
sm_statetable.c sctp: fix checkpatch errors with indent 2013-12-26 13:47:48 -05:00
socket.c sctp: translate network order to host order when users get a hmacid 2016-02-09 04:53:16 -05:00
ssnmap.c sctp: Fix FSF address in file headers 2013-12-06 12:37:56 -05:00
sysctl.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-01-11 23:55:43 -05:00
transport.c sctp: remove the dead field of sctp_transport 2016-01-28 15:59:32 -08:00
tsnmap.c sctp: Fix FSF address in file headers 2013-12-06 12:37:56 -05:00
ulpevent.c sctp: Fixup v4mapped behaviour to comply with Sock API 2014-07-31 21:49:06 -07:00
ulpqueue.c net: introduce SO_INCOMING_CPU 2014-11-11 13:00:06 -05:00