CVE-2026-53337: net: bonding: fix NULL pointer dereference in bond_do_ioctl()

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

net: bonding: fix NULL pointer dereference in bonddoioctl()

In bonddoioctl(), slavedev is obtained via devgetbyname() which can return NULL if the requested interface name does not exist. However, the subsequent slavedbg() call is placed before the NULL check:

slavedev = devgetbyname(net, ifr->ifrslave); slavedbg(bonddev, slavedev, "slavedev=%p:\n", slavedev); //here if (!slavedev) return -ENODEV;

The slavedbg() macro expands to netdevdbg(bonddev, "(slave %s): " fmt, (slavedev)->name, ...) which unconditionally dereferences slavedev->name before the NULL check is performed. This results in a NULL pointer dereference kernel oops when a user calls bonding ioctl (e.g. SIOCBONDENSLAVE, SIOCBONDRELEASE, etc.) with a non-existent slave interface name.

This is reachable from userspace via the bonding ioctl interface with CAPNETADMIN capability, making it a potential local denial-of-service vector.

Fix by moving the slavedbg() call after the NULL check.