CVE-2025-21993 Information

Description

In the Linux kernel the following vulnerability has been resolved:

iscsi_ibft: Fix UBSAN shift-out-of-bounds warning in ibft_attr_show_nic()

When performing an iSCSI boot using IPv6 iscsistart still reads the /sys/firmware/ibft/ethernetX/subnet-mask entry. Since the IPv6 prefix length is 64 this causes the shift exponent to become negative triggering a UBSAN warning. As the concept of a subnet mask does not apply to IPv6 the value is set to ~0 to suppress the warning message.

Reference

https://git.kernel.org/stable/c/07e0d99a2f701123ad3104c0f1a1e66bce74d6e5 https://git.kernel.org/stable/c/2d1eef248107bdf3d5a69d0fde04c30a79a7bf5d https://git.kernel.org/stable/c/9bfa80c8aa4e06dff55a953c3fffbfc68a3a3b1c https://git.kernel.org/stable/c/b253660fac5e0e9080d2c95e3a029e1898d49afb https://git.kernel.org/stable/c/c1c6e527470e5eab0b2d57bd073530fbace39eab