Jaroslava Fiedlerova
8dfb61827b
nr rlc: tolerate bogus data Some unfriendly entity may play with the RLC module and send bogus data to trigger funky behaviors here and there. A report sent by Dhanish indentifies one such issue. From analyzing this report, a possible scenario is the following. Unfriendly entity sends an RLC PDU with: is_first=0 is_last=0 so=15 lenght of data, whatever, let's say 1. This PDU is put in the RX list. Then later it sends another PDU (for the same SN, obviously), with: is_first=1 is_last=1 so=0 (well, since is_first=1, necessarily so=0; it is not transmitted, see 38.322 6.2.2.3 for UM and 38.322 6.2.2.4 for AM) length=10, let's say. This PDU is also put in the RX list, before the previous one. Then the function sdu_full() returns 1, so reassemble_and_deliver() is called and the 'while (pdu)' loop is executed for both PDUs. When the second (bogus one) is processed, so==10 (after processing the first PDU) and the line: int len = pdu->size - (so - pdu->so) is: int len = 1 - (10 - 15) which is not good. So we detect the case 'pdu->so > so' and reject the SDU. We could label the other entity as bogus, since no standard RLC implementation will produce such a case, but let's remain friendly, even with unfriendly entities. (To be changed later if needed.) The problem was reported for RLC AM but is also present in RLC UM. (Not in RLC TM, where there is no segmentation.) Note: according to the report, this bug was found using a fuzzer described as 'AI-assisted custom 5G NR protocol fuzzer'. It had to be said.
OpenAirInterface License
The source code is distributed under CSSL v1.0. Some files, such as for orchestration, are distributed under MIT license(MIT.txt). Documentation is distributed under Creative Commons Attribution 4.0 International license.
All the files without an explicit copyright header have an implicit "Copyright of OpenAirInterface Authors".
Please see NOTICE for other licenses which are used in the software.
In the past OAI source code has been re-licensed sometimes, here is the history:
- CSSL v1.0 starting tag 2026.w14
- OAI Public License v1.1 starting tag v1.0 till
af4b0d53 - OAI Public License v1.0: starting tag v.04 till v1.0
- GPL 3: starting tag v.0 till v.04 (only initial implementation of 4G)
Where to Start
- General overview of documentation
- The implemented features
- System Requirements for Using OAI Stack
- How to build
- How to run the modems
Not all information is available in a central place, and information for specific sub-systems might be available in the corresponding sub-directories. To find all READMEs, this command might be handy:
find . -iname "readme*"
RAN repository structure
The OpenAirInterface (OAI) software is composed of the following parts:
openairinterface5g
├── charts
├── ci-scripts : Meta-scripts used by the OSA CI process. Contains also configuration files used day-to-day by CI.
├── CMakeLists.txt : Top-level CMakeLists.txt for building
├── cmake_targets : Build utilities to compile (simulation, emulation and real-time platforms), and generated build files.
├── common : Some common OAI utilities, some other tools can be found at openair2/UTILS.
├── doc : Documentation
├── docker : Dockerfiles to build for Ubuntu and RHEL
├── executables : Top-level executable source files (gNB, eNB, ...)
├── maketags : Script to generate emacs tags.
├── nfapi : (n)FAPI code for MAC-PHY interface
├── openair1 : Layer 1 (3GPP LTE Rel-10/12 PHY, NR Rel-15 PHY)
├── openair2 : Layer 2 (3GPP LTE Rel-10 MAC/RLC/PDCP/RRC/X2AP, LTE Rel-14 M2AP, NR Rel-15+ MAC/RLC/PDCP/SDAP/RRC/X2AP/F1AP/E1AP), E2AP
├── openair3 : Layer 3 (3GPP LTE Rel-10 S1AP/GTP, NR Rel-15 NGAP/GTP)
├── openshift : OpenShift helm charts for some deployment options of OAI
├── radio : Drivers for various radios such as USRP, AW2S, RFsim, 7.2 FHI, ...
├── targets : Some configuration files; only historical relevance, and might be deleted in the future
└── tools : Tools for use by the developers/ci machines: code analysis and formatting
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