CyberRota Analysis
AI-GeneratedThe vulnerability affects the Linux kernel's u32 classifier, where insufficient validation of the user-provided `offshift` value can lead to shift-out-of-bounds errors, potentially allowing unprivileged users to exploit this flaw. This can result in undefined behavior when processing network packets, which may compromise system stability or security. System administrators and developers managing Linux environments should prioritize applying the fix to mitigate potential exploitation risks.
Original NVD Description
In the Linux kernel, the following vulnerability has been resolved: net/sched: cls_u32: validate offshift to prevent shift-out-of-bounds u32_change() copies the user-provided tc_u32_sel.offshift (unsigned char, 0-255) into the kernel knode object without bounds validation. When a packet later hits u32_classify() with TC_U32_VAROFFSET set, it evaluates `ntohs(offmask & *data) >> offshift` where the left operand is a 16-bit value promoted to a 32-bit int. Any offshift >= 32 is undefined behavior per C11 6.5.7p3, triggerable by an unprivileged user via user/network namespaces. UBSAN: shift-out-of-bounds in net/sched/cls_u32.c:236:43 shift exponent 32 is too large for 32-bit type int Fix this by rejecting offshift >= 16 during filter creation in u32_change().