Fix out-of-bounds reads in IcmpLayer getters on truncated packets - #2240
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Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## dev #2240 +/- ##
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+ Coverage 82.73% 82.77% +0.03%
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Files 333 333
Lines 60372 60407 +35
Branches 12866 12880 +14
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+ Hits 49947 50000 +53
+ Misses 9549 9531 -18
Partials 876 876
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Every get*Data() method checked only the ICMP message type before casting the layer buffer to the fixed-size structure that type implies, so a truncated capture produced an IcmpLayer shorter than the structure it claims to be and reading any field past the layer was out of bounds. Route those getters through a castMessageData() helper that requires the whole structure to be present, and tighten isDataValid() accordingly. Assisted-By: Claude Opus 5 <noreply@anthropic.com>
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| /// a timestamp of when the message was sent. Not part of the RFC 792 echo header, these are the first 8 | ||
| /// bytes of the echo payload, and they are absent from a message shorter than sizeof(icmp_echo_hdr) | ||
| uint64_t timestamp; | ||
| } icmp_echo_hdr; |
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I didn't know that timestamp isn't part of the RFC. In that case we might need a breaking change here:
- Remove
timestampfrom the struct (that way we no longer needICMP_ECHO_MIN_LEN) - Add 2 methods to
icmp_echo_requestthat returns the timestamp if exists:bool hasTimestamp()uint64_t getTimetamp()
| // ICMP_INFO_REQUEST, ICMP_INFO_REPLY | ||
| if (type == 15 || type == 16) | ||
| return dataLen >= sizeof(icmp_info_request); | ||
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If I understand correctly, this is the only change that is related to the PR description. The other changes are separate. Maybe we can break this PR to multiple PRs?
- The first contains only this change (and tests)
- Another PR for making
timestampoptional in echo request (and tests) - A last PR for fixing
getRouterAddress()(if you prefer to open less PRs, you can include it in the second PR because it's pretty minor change
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Can you include the pcap file for this packet? That way it'd be easier to view it in Wireshark
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Hi,
we ran into an out-of-bounds read ASAN report with the
FuzzTarget.cppharness:The input is included in this PR under
Tests/Fuzzers/RegressionTests/regression_samples/crash-icmp-info-request-truncated.The
getX()methods inIcmpLayer.hcurrently only check the type field, and return a casted struct without verifying that the underlying buffer has enough data. This PR adjusts these getters to returnnullptrin the case of packets without enough data. It also adds a test that verifies this behaviour for various ICMP message types.Thanks!
Found by the CISPA Fandango team while triaging findings in oss-fuzz harnesses.