diff options
Diffstat (limited to 'pkg/tcpip/network/ipv4/ipv4.go')
| -rw-r--r-- | pkg/tcpip/network/ipv4/ipv4.go | 18 |
1 files changed, 11 insertions, 7 deletions
diff --git a/pkg/tcpip/network/ipv4/ipv4.go b/pkg/tcpip/network/ipv4/ipv4.go index fa4ae2012..f4394749d 100644 --- a/pkg/tcpip/network/ipv4/ipv4.go +++ b/pkg/tcpip/network/ipv4/ipv4.go @@ -404,11 +404,15 @@ func (e *endpoint) HandlePacket(r *stack.Route, pkt *stack.PacketBuffer) { return } // The packet is a fragment, let's try to reassemble it. - last := h.FragmentOffset() + uint16(pkt.Data.Size()) - 1 - // Drop the packet if the fragmentOffset is incorrect. i.e the - // combination of fragmentOffset and pkt.Data.size() causes a - // wrap around resulting in last being less than the offset. - if last < h.FragmentOffset() { + start := h.FragmentOffset() + // Drop the fragment if the size of the reassembled payload would exceed the + // maximum payload size. + // + // Note that this addition doesn't overflow even on 32bit architecture + // because pkt.Data.Size() should not exceed 65535 (the max IP datagram + // size). Otherwise the packet would've been rejected as invalid before + // reaching here. + if int(start)+pkt.Data.Size() > header.IPv4MaximumPayloadSize { r.Stats().IP.MalformedPacketsReceived.Increment() r.Stats().IP.MalformedFragmentsReceived.Increment() return @@ -425,8 +429,8 @@ func (e *endpoint) HandlePacket(r *stack.Route, pkt *stack.PacketBuffer) { ID: uint32(h.ID()), Protocol: proto, }, - h.FragmentOffset(), - last, + start, + start+uint16(pkt.Data.Size())-1, h.More(), proto, pkt.Data, |