Hardening: only dispatch UDP messages that are valid on UDP - #229
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Response handler tables are shared between TCP and the UDP. TCP handlers operate on a connection (channels, IOIDs, security session, ...) and down-cast the transport with an unchecked static_pointer_cast. A single unsolicited datagram carrying e.g. CMD_CREATE_CHANNEL makes the server create a channel through that invalid pointer. It reliably segfaults in ServerChannelRequesterImpl::getPeerInfo(). Restrict processBuffer() to the messages that are actually defined for UDP (beacon, echo, search, search response, origin tag) and drop the rest. Also drop truncated CMD_ORIGIN_TAG messages: decodeAsIPv6Address() does not check the buffer, so a shorter message reads past the end of the receive buffer and trips the ByteBuffer assertion. epicsAssert() suspends the calling thread - the IOC stops answering searches on that interface. Found while investigating epics-base#228. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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| Metric | Results |
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| Complexity | 10 |
| Duplication | 0 |
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✅ Build pvAccessCPP 1.0.168 completed (commit b5788f1102 by @ralphlange) |
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Response handler tables are shared between TCP and the UDP. TCP handlers operate on a connection (channels, IOIDs, security session, ...) and down-cast the transport with an unchecked static_pointer_cast.
A single unsolicited datagram carrying e.g. CMD_CREATE_CHANNEL makes the server create a channel through that invalid pointer. It reliably segfaults in ServerChannelRequesterImpl::getPeerInfo().
Restrict processBuffer() to the messages that are actually defined for UDP (beacon, echo, search, search response, origin tag) and drop the rest.
Also drop truncated CMD_ORIGIN_TAG messages:
decodeAsIPv6Address() does not check the buffer, so a shorter message reads past the end of the receive buffer and trips the ByteBuffer assertion. epicsAssert() suspends the calling thread - the IOC stops answering searches on that interface.
Found while investigating #228.