When an ICMPV6_PKT_TOOBIG message is received with a MTU below 1280,
all further packets include a fragment header.
Unlike regular defragmentation, conntrack also needs to "reassemble"
those fragments in order to obtain a packet without the fragment
header for connection tracking. Currently nf_conntrack_reasm checks
whether a fragment has either IP6_MF set or an offset != 0, which
makes it ignore those fragments.
Remove the invalid check and make reassembly handle fragment queues
containing only a single fragment.
Reported-and-tested-by: Ulrich Weber <uweber@astaro.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
9e2dcf7202