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  1. 17 6月, 2008 9 次提交
  3. 15 6月, 2008 1 次提交
  5. 13 6月, 2008 1 次提交
    • D
      tcp: Revert 'process defer accept as established' changes. · ec0a1966
      由 David S. Miller 提交于 
      This reverts two changesets, ec3c0982
("[TCP]: TCP_DEFER_ACCEPT updates - process as established") and
the follow-on bug fix 9ae27e0a
("tcp: Fix slab corruption with ipv6 and tcp6fuzz").

This change causes several problems, first reported by Ingo Molnar
as a distcc-over-loopback regression where connections were getting
stuck.

Ilpo Järvinen first spotted the locking problems.  The new function
added by this code, tcp_defer_accept_check(), only has the
child socket locked, yet it is modifying state of the parent
listening socket.

Fixing that is non-trivial at best, because we can't simply just grab
the parent listening socket lock at this point, because it would
create an ABBA deadlock.  The normal ordering is parent listening
socket --> child socket, but this code path would require the
reverse lock ordering.

Next is a problem noticed by Vitaliy Gusev, he noted:

----------------------------------------
>--- a/net/ipv4/tcp_timer.c
>+++ b/net/ipv4/tcp_timer.c
>@@ -481,6 +481,11 @@ static void tcp_keepalive_timer (unsigned long data)
> 		goto death;
> 	}
>
>+	if (tp->defer_tcp_accept.request && sk->sk_state == TCP_ESTABLISHED) {
>+		tcp_send_active_reset(sk, GFP_ATOMIC);
>+		goto death;

Here socket sk is not attached to listening socket's request queue. tcp_done()
will not call inet_csk_destroy_sock() (and tcp_v4_destroy_sock() which should
release this sk) as socket is not DEAD. Therefore socket sk will be lost for
freeing.
----------------------------------------

Finally, Alexey Kuznetsov argues that there might not even be any
real value or advantage to these new semantics even if we fix all
of the bugs:

----------------------------------------
Hiding from accept() sockets with only out-of-order data only
is the only thing which is impossible with old approach. Is this really
so valuable? My opinion: no, this is nothing but a new loophole
to consume memory without control.
----------------------------------------

So revert this thing for now.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      ec0a1966
  7. 12 6月, 2008 5 次提交
  9. 11 6月, 2008 3 次提交
  11. 10 6月, 2008 4 次提交
  13. 06 6月, 2008 1 次提交
  15. 05 6月, 2008 7 次提交
    • O
      tcp: Fix for race due to temporary drop of the socket lock in skb_splice_bits. · 293ad604
      由 Octavian Purdila 提交于 
      skb_splice_bits temporary drops the socket lock while iterating over
the socket queue in order to break a reverse locking condition which
happens with sendfile. This, however, opens a window of opportunity
for tcp_collapse() to aggregate skbs and thus potentially free the
current skb used in skb_splice_bits and tcp_read_sock.

This patch fixes the problem by (re-)getting the same "logical skb"
after the lock has been temporary dropped.

Based on idea and initial patch from Evgeniy Polyakov.
Signed-off-by: NOctavian Purdila <opurdila@ixiacom.com>
Acked-by: NEvgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      293ad604
    • S
      tcp: Increment OUTRSTS in tcp_send_active_reset() · 26af65cb
      由 Sridhar Samudrala 提交于 
      TCP "resets sent" counter is not incremented when a TCP Reset is 
sent via tcp_send_active_reset().
Signed-off-by: NSridhar Samudrala <sri@us.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      26af65cb
    • D
      raw: Raw socket leak. · 22dd4850
      由 Denis V. Lunev 提交于 
      The program below just leaks the raw kernel socket

int main() {
        int fd = socket(PF_INET, SOCK_RAW, IPPROTO_UDP);
        struct sockaddr_in addr;

        memset(&addr, 0, sizeof(addr));
        inet_aton("127.0.0.1", &addr.sin_addr);
        addr.sin_family = AF_INET;
        addr.sin_port = htons(2048);
        sendto(fd,  "a", 1, MSG_MORE, &addr, sizeof(addr));
        return 0;
}

Corked packet is allocated via sock_wmalloc which holds the owner socket,
so one should uncork it and flush all pending data on close. Do this in the
same way as in UDP.
Signed-off-by: NDenis V. Lunev <den@openvz.org>
Acked-by: NAlexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      22dd4850
    • I
      tcp: fix skb vs fack_count out-of-sync condition · a6604471
      由 Ilpo Järvinen 提交于 
      This bug is able to corrupt fackets_out in very rare cases.
In order for this to cause corruption:
  1) DSACK in the middle of previous SACK block must be generated.
  2) In order to take that particular branch, part or all of the
     DSACKed segment must already be SACKed so that we have that
     in cache in the first place.
  3) The new info must be top enough so that fackets_out will be
     updated on this iteration.
...then fack_count is updated while skb wasn't, then we walk again
that particular segment thus updating fack_count twice for
a single skb and finally that value is assigned to fackets_out
by tcp_sacktag_one.

It is safe to call tcp_sacktag_one just once for a segment (at
DSACK), no need to call again for plain SACK.

Potential problem of the miscount are limited to premature entry
to recovery and to inflated reordering metric (which could even
cancel each other out in the most the luckiest scenarios :-)).
Both are quite insignificant in worst case too and there exists
also code to reset them (fackets_out once sacked_out becomes zero
and reordering metric on RTO).

This has been reported by a number of people, because it occurred
quite rarely, it has been very evasive. Andy Furniss was able to
get it to occur couple of times so that a bit more info was
collected about the problem using a debug patch, though it still
required lot of checking around. Thanks also to others who have
tried to help here.

This is listed as Bugzilla #10346. The bug was introduced by
me in commit 68f8353b ([TCP]: Rewrite SACK block processing & 
sack_recv_cache use), I probably thought back then that there's
need to scan that entry twice or didn't dare to make it go
through it just once there. Going through twice would have
required restoring fack_count after the walk but as noted above,
I chose to drop the additional walk step altogether here.
Signed-off-by: NIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      a6604471
    • D
      [IPV6]: inet_sk(sk)->cork.opt leak · 36d926b9
      由 Denis V. Lunev 提交于 
      IPv6 UDP sockets wth IPv4 mapped address use udp_sendmsg to send the data
actually. In this case ip_flush_pending_frames should be called instead
of ip6_flush_pending_frames.
Signed-off-by: NDenis V. Lunev <den@openvz.org>
Signed-off-by: NYOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
      36d926b9
    • Y
      [IPV4] TUNNEL4: Fix incoming packet length check for inter-protocol tunnel. · baa2bfb8
      由 YOSHIFUJI Hideaki 提交于 
      Signed-off-by: NYOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
      baa2bfb8
    • I
      tcp: Fix inconsistency source (CA_Open only when !tcp_left_out(tp)) · 8aca6cb1
      由 Ilpo Järvinen 提交于 
      It is possible that this skip path causes TCP to end up into an
invalid state where ca_state was left to CA_Open while some
segments already came into sacked_out. If next valid ACK doesn't
contain new SACK information TCP fails to enter into
tcp_fastretrans_alert(). Thus at least high_seq is set
incorrectly to a too high seqno because some new data segments
could be sent in between (and also, limited transmit is not
being correctly invoked there). Reordering in both directions
can easily cause this situation to occur.

I guess we would want to use tcp_moderate_cwnd(tp) there as well
as it may be possible to use this to trigger oversized burst to
network by sending an old ACK with huge amount of SACK info, but
I'm a bit unsure about its effects (mainly to FlightSize), so to
be on the safe side I just currently fixed it minimally to keep
TCP's state consistent (obviously, such nasty ACKs have been
possible this far). Though it seems that FlightSize is already
underestimated by some amount, so probably on the long term we
might want to trigger recovery there too, if appropriate, to make
FlightSize calculation to resemble reality at the time when the
losses where discovered (but such change scares me too much now
and requires some more thinking anyway how to do that as it
likely involves some code shuffling).

This bug was found by Brian Vowell while running my TCP debug
patch to find cause of another TCP issue (fackets_out
miscount).
Signed-off-by: NIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      8aca6cb1
  17. 04 6月, 2008 3 次提交
  19. 22 5月, 2008 6 次提交