ovpn: replace bind when clearing stale local source

Overview

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

ovpn: replace bind when clearing stale local source

The UDP output fallback clears bind->local in place when the remembered source address is no longer usable. The bind is RCU-published and read locklessly by concurrent TX, so an IPv6 reader can observe a torn address.

Retry the route lookup with source address autoselection without modifying the bind. After a successful lookup, revalidate the bind and route key under peer->lock, reset the dst cache, and best-effort publish a replacement bind with a wildcard local address.

Do not cache the resolved dst when clearing the local source. Replacing the source invalidates all per-CPU cache entries, while dst_cache_set_ip4 and dst_cache_set_ip6 update only the current CPU slot. The current packet can still use the resolved route; if bind allocation fails, a later cache miss retries the repair.

Affected

• Linux >= 08857b5ec5d91d83e69e40a36554a8c7557b7301 < c44a04722f7dae9a45a101b8e100931ab59f1c18
• Linux >= 08857b5ec5d91d83e69e40a36554a8c7557b7301 < 72bd1bea37ea2c8553938f086bf48ccd2147dfe1
• Linux >= 08857b5ec5d91d83e69e40a36554a8c7557b7301 < 7d8104988f423572df1f3347ce578037b1043f34
• Linux 6.16

Remediation

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