Medium [CVE-2026-80610] fix potential divide-by-zero when num_vsi is zero

In the Linux kernel, the following vulnerability has been resolved: net: enetc: fix potential divide-by-zero when num_vsi is zero For i.MX94 series, all the standalone ENETCs do not support SR-IOV, so pf->caps.num_vsi is zero. This leads to a divide-by-zero in enetc4_default_rings_allocation() when distributing rings among PF and VFs.

Division by zero is undefined behavior in C. On ARM64, the UDIV/SDIV instructions silently return zero rather than raising an exception, so the issue does not cause a visible crash.

However, relying on this behavior is incorrect and poses a cross-platform compatibility risk. Add an explicit check for num_vsi == 0 and return early after the PF's rings have been configured.

When the `num_vsi` value is zero, a divide-by-zero error occurs during the allocation of network rings. While this issue may not cause an immediate system crash on some architectures, it represents undefined behavior that could lead to system instability or unexpected operational issues, particularly across different computing platforms.

Red Hat severity: Moderate — CVSS 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H). Weakness: CWE-369.

Red Hat lists Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9 as not affected.