CVE-2026-43139 xfrm6: fix uninitialized saddr in xfrm6_get_saddr()

In the Linux kernel, the following vulnerability has been resolved: xfrm6: fix uninitialized saddr in xfrm6getsaddr xfrm6getsaddr does not check the return value of ipv6devgetsaddr. When ipv6devgetsaddr fails to find a suitable source address returns -EADDRNOTAVAIL, saddr-in6 is left uninitialize...