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author | Jerry Chu <hkchu@google.com> | 2012-10-22 11:26:36 (GMT) |
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committer | David S. Miller <davem@davemloft.net> | 2012-10-23 06:42:56 (GMT) |
commit | 37561f68bd527ec39076e32effdc7b1dcdfb17ea (patch) | |
tree | 3b15ff453617ee5ef52e5f7a9885770b4172bc0a /drivers/net/can/flexcan.c | |
parent | 0b63bf1fe6f9ed1ec4148e8896f4522e08476b80 (diff) | |
download | linux-fsl-qoriq-37561f68bd527ec39076e32effdc7b1dcdfb17ea.tar.xz |
tcp: Reject invalid ack_seq to Fast Open sockets
A packet with an invalid ack_seq may cause a TCP Fast Open socket to switch
to the unexpected TCP_CLOSING state, triggering a BUG_ON kernel panic.
When a FIN packet with an invalid ack_seq# arrives at a socket in
the TCP_FIN_WAIT1 state, rather than discarding the packet, the current
code will accept the FIN, causing state transition to TCP_CLOSING.
This may be a small deviation from RFC793, which seems to say that the
packet should be dropped. Unfortunately I did not expect this case for
Fast Open hence it will trigger a BUG_ON panic.
It turns out there is really nothing bad about a TFO socket going into
TCP_CLOSING state so I could just remove the BUG_ON statements. But after
some thought I think it's better to treat this case like TCP_SYN_RECV
and return a RST to the confused peer who caused the unacceptable ack_seq
to be generated in the first place.
Signed-off-by: H.K. Jerry Chu <hkchu@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/can/flexcan.c')
0 files changed, 0 insertions, 0 deletions