libosmo-abis 1.4.2 and 1.5.2 patch relases
A critical bug has been discovered in libosmo-abis: the calculation of the TCP keepalive user timeout value was incorrect. This issue remained unnoticed for quite some time, ever since the initial support for TCP_USER_TIMEOUT was merged back in Jun 2019 (libosmo-abis >= 0.7.0). However, since it was not yet enabled by default at that time, only users with explicit TCP keepalive configuration in their config files would be affected. The TCP keepalive was later enabled by default in Nov 2022 (libosmo-abis >= 1.4.0), impacting all users and resulting in a significantly shorter TCP_USER_TIMEOUT value than expected.
The problem has been fixed in master. Patch releases tagged for two latest minor versions:
| Release | Tag |
|---|---|
| 1.4.2 | https://gitea.osmocom.org/osmocom/libosmo-abis/releases/tag/1.4.2 |
| 1.5.2 | https://gitea.osmocom.org/osmocom/libosmo-abis/releases/tag/1.5.2 |
This issue primarily impacted production users operating IPA connections (A-bis/OML, A-bis/RSL, GSUP) over links with delays with RTT approaching one second, such as overloaded/flakey WiFi links or VSAT back-haul. It is unlikely to have affected users with non-overloaded terrestrial/wired back-haul.
