CVE-2026-31423 PUBLISHED

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

Assigner: Linux
Reserved: 09.03.2026 Published: 13.04.2026 Updated: 13.04.2026

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.

Product Status

Vendor Linux
Product Linux
Versions Default: unaffected
  • affected from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to 25b6821884713a31e2b49fb67b0ebd765b33e0a9 (excl.)
  • affected from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to c56f78614e7781aaceca9bd3cb2128bf7d45c3bd (excl.)
  • affected from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to b9e6431cbea8bb1fae8069ed099b4ee100499835 (excl.)
  • affected from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to 17c1b9807b8a67d676b6dcf749ee932ebaa7f568 (excl.)
  • affected from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to d0aefec1b1a1ba2c1d251028dc2c4e5b4ce1fea5 (excl.)
  • affected from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to 4576100b8cd03118267513cafacde164b498b322 (excl.)
Vendor Linux
Product Linux
Versions Default: affected
  • Version 2.6.12 is affected
  • unaffected from 0 to 2.6.12 (excl.)
  • unaffected from 6.1.168 to 6.1.* (incl.)
  • unaffected from 6.6.134 to 6.6.* (incl.)
  • unaffected from 6.12.81 to 6.12.* (incl.)
  • unaffected from 6.18.22 to 6.18.* (incl.)
  • unaffected from 6.19.12 to 6.19.* (incl.)
  • unaffected from 7.0 to * (incl.)

References