forked from acouzens/open5gs
3886891833
A race condition can occur in the following situations. In conclusion, we can use this situation to determine whether or not the UE Context has been removed and avoiding a crash. For example, suppose a UE Context is removed in the followings. 1. Attach Request 2. Authentication-Information-Request 3. Authentication-Information-Answer 4. Authentication Request 5. Authentication Response(MAC Failed) 6. Authentication Reject 7. UEContextReleaseCommand 8. UEContextReleaseComplete The MME then sends a Purge-UE-request to the HSS and deletes the UE context as soon as it receives a Purge-UE-Answer. Suppose an Attach Request is received from the same UE between Purge-UE-Request/Answer, then the MME and HSS start the Authentication-Information-Request/Answer process. This can lead to the following situations. 1. Purge-UE-Request 2. Attach Request 3. Authentication-Information-Request 4. Purge-UE-Answer 5. [UE Context Removed] 6. Authentication-Information-Answer Since the UE Context has already been deleted when the Authentication-Information-Answer is received, it cannot be processed properly. Therefore, mme_ue_cycle() is used to check whether the UE Context has been deleted and decide whether to process or ignore the Authentication-Information-Answer as shown below. |
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| .. | ||
| amf | ||
| ausf | ||
| bsf | ||
| hss | ||
| mme | ||
| nrf | ||
| nssf | ||
| pcf | ||
| pcrf | ||
| scp | ||
| sepp | ||
| sgwc | ||
| sgwu | ||
| smf | ||
| udm | ||
| udr | ||
| upf | ||
| main.c | ||
| meson.build | ||