Linux Kernel Divide-By-Zero Vulnerability in HFSC Scheduler

A divide-by-zero vulnerability has been identified in the Linux kernel's High-Performance Scheduler (HFSC) implementation. This issue arises in the 'rtsc_min()' function, where a u32 variable, 'dsm', is used as a divisor. For large input values, the calculation can produce a result that exceeds the maximum limit of a 32-bit integer, leading to a truncation that yields zero. This, in turn, causes a divide-by-zero error, disrupting the normal processing of concave-curve intersections. The vulnerability affects several versions of the Linux kernel.

Impact

Exploitation of this vulnerability leads to a divide-by-zero error, causing a kernel oops in the HFSC scheduler's 'rtsc_min()' function.

Reproduction

The vulnerability can be reproduced by configuring the HFSC scheduler with large slope values that cause the m2sm() function to output a value exceeding 2^32. When 'rtsc_min()' is called with these parameters, the 'dsm' variable will be incorrectly truncated to zero, creating a divide-by-zero situation.

Remediation

The vulnerability has been fixed in the Linux kernel. Users should upgrade to the latest version.