CVE-2026-31411 net: atm: fix crash due to unvalidated vcc pointer in sigd_send()

In the Linux kernel, the following vulnerability has been resolved: net: atm: fix crash due to unvalidated vcc pointer in sigdsend Reproducer available at 1. The ATM send path sendmsg - vccsendmsg - sigdsend reads the vcc pointer from msg-vcc and uses it directly without any validation. This...