CVE-2026-64095

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> batman-adv: bla: avoid double decrement of bla.num_requests<br /> <br /> The bla.num_requests is increased when no request_sent was in progress. And<br /> it is decremented in various places (announcement was received, backbone is<br /> purged, periodic work). But the check if the request_sent is actually set<br /> to a specific state and the atomic_dec/_inc are not safe because they are<br /> not atomic (TOCTOU) and multiple such code portions can run concurrently.<br /> <br /> At the same time, it is necessary to modify request_sent (state) and<br /> bla.num_requests atomically. Otherwise batadv_bla_send_request() might set<br /> request_sent to 1 and is interrupted. batadv_handle_announce() can then<br /> set request_sent back to 0 and decrement num_requests before<br /> batadv_bla_send_request() incremented it.<br /> <br /> The two operations must therefore be locked. And since state (request_sent)<br /> and wait_periods are only accessed inside this lock, they can be converted<br /> to simpler datatypes. And to avoid that the bla.num_requests is touched by<br /> a parallel running context with a valid backbone_gw reference after<br /> batadv_bla_purge_backbone_gw() ran, a third state "stopped" is required to<br /> correctly signal that a backbone_gw is in the state of being cleaned up.