CVE-2026-31423

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

net/sched: sch_hfsc: fix divide-by-zero in rtsc_min()

m2sm() converts a u32 slope to a u64 scaled value. For large inputs

(e.g. m1=4000000000), the result can reach 2^32. rtsc_min() stores

the difference of two such u64 values in a u32 variable `dsm` and

uses it as a divisor. When the difference is exactly 2^32 the

truncation yields zero, causing a divide-by-zero oops in the

concave-curve intersection path:

Oops: divide error: 0000

RIP: 0010:rtsc_min (net/sched/sch_hfsc.c:601)

Call Trace:

init_ed (net/sched/sch_hfsc.c:629)

hfsc_enqueue (net/sched/sch_hfsc.c:1569)

[...]

Widen `dsm` to u64 and replace do_div() with div64_u64() so the full

difference is preserved.