path: root/net/ipv4/tcp_timer.c
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authorLinus Lüssing <linus.luessing@c0d3.blue>2017-07-06 07:02:25 +0200
committerSimon Wunderlich <sw@simonwunderlich.de>2017-07-31 11:17:38 +0200
commit54e22f265e872ae140755b3318521d400a094605 (patch)
treef314b63fadb1a534fc0b4938d3e9e57cb73486da /net/ipv4/tcp_timer.c
parentLinux v4.13-rc1 (diff)
batman-adv: fix TT sync flag inconsistencies
This patch fixes an issue in the translation table code potentially leading to a TT Request + Response storm. The issue may occur for nodes involving BLA and an inconsistent configuration of the batman-adv AP isolation feature. However, since the new multicast optimizations, a single, malformed packet may lead to a mesh-wide, persistent Denial-of-Service, too. The issue occurs because nodes are currently OR-ing the TT sync flags of all originators announcing a specific MAC address via the translation table. When an intermediate node now receives a TT Request and wants to answer this on behalf of the destination node, then this intermediate node now responds with an altered flag field and broken CRC. The next OGM of the real destination will lead to a CRC mismatch and triggering a TT Request and Response again. Furthermore, the OR-ing is currently never undone as long as at least one originator announcing the according MAC address remains, leading to the potential persistency of this issue. This patch fixes this issue by storing the flags used in the CRC calculation on a a per TT orig entry basis to be able to respond with the correct, original flags in an intermediate TT Response for one thing. And to be able to correctly unset sync flags once all nodes announcing a sync flag vanish for another. Fixes: e9c00136a475 ("batman-adv: fix tt_global_entries flags update") Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue> Acked-by: Antonio Quartulli <a@unstable.cc> [sw: typo in commit message] Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
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