ovpn: replace bind when learning local endpoint

Overview

In the Linux kernel, the following vulnerability has been resolved:

ovpn: replace bind when learning local endpoint

struct ovpn_bind is published through peer->bind with RCU, but local endpoint learning updates bind->local in place under peer->lock. UDP TX reads the field without that lock. In particular, a concurrent IPv6 update can therefore result in a torn address read.

Use ovpn_peer_reset_sockaddr to publish a replacement bind when learning a new local endpoint, just as a remote endpoint change does. Preserve the current remote address and reset the dst cache only after the new bind has been published successfully.

Track remote endpoint changes separately so that float notification and transport-address rehashing remain limited to actual peer floats.

Affected

• Linux >= f0281c1d3732d1ec084fa1e06d1767d33e1a570e < 21dbc9f4d0bdd3b22f91beabc7840064bf11594f
• Linux >= f0281c1d3732d1ec084fa1e06d1767d33e1a570e < e283009151d3d131447c2edda500199c5fda5f72
• Linux >= f0281c1d3732d1ec084fa1e06d1767d33e1a570e < aea934a221ec6a867221e5b765f65f1857befd53
• Linux 6.16

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.