A use-after-free vulnerability was found in the Linux kernel's IPv6 FIB rule lookup path. In fib6rulesuppress(), when a route is suppressed and released via ip6rtputflags(), the res->rt6 pointer is not cleared. If no later rule supplies a replacement route, fib6rulelookup() returns the stale (freed) rt6info to its caller. The subsequent dstrelease() then operates on freed memory, hitting rcurefputslowpath(). A local attacker who can configure IPv6 routing/FIB rules could trigger this to cause a denial of service (kernel crash) or potentially escalate privileges.

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

net: bridge: stop fast-leave after deleting a port group

brmulticastleavegroup() iterates mp->ports with pp = &p->next in its fast-leave path. After brmulticastdelpg() removes p, continuing the loop advances pp through the deleted entry.

If multicast-to-unicast was enabled, the bridge can hold multiple port groups for the same port and group with different source MAC addresses. Once multicast-to-unicast is disabled, brportgroupequal() matches those entries by port only. A fast leave can then delete one entry and continue from its stale next pointer, leaving mp->ports pointing at a deleted port group.

Fast leave only needs to remove one matching port group. Break after brmulticastdelpg() so the loop stops before dereferencing the removed entry.