CVE-2026-98085

Summary

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

bpf: backtrack_insn(): Handle ld_{abs,ind} subprog exit edge

Nicholas Carlini reported a bug in precision backtracking mechanism for BPF_LD | BPF_{IND,ABS} instructions. These instructions are modelled as two branches:

  • fallthrough;
  • implicit exit from current subprogram.

The implicit exit case was not handled by the backtrack_insn() function. When backtracking such a path backtrack_insn() did not call bt_subprog_enter(), which meant that backtracking continued manipulating precision marks in a caller frame, while looking at instructions in a callee frame.

This lead to segmentation faults during verification (see the selftest), or unsound state pruning.

Affected Software

VendorProductVersion RangeStatus
LinuxLinuxee861486e377edc55361c08dcbceab3f6b6577bd < 671b7b9a660ef15b25faa3df161205b9dc8d1eb2affected
LinuxLinuxee861486e377edc55361c08dcbceab3f6b6577bd < 387b1baefbb776e3f48dc2261e77a49213f470f7affected
LinuxLinux928d354ae3557e8f755a227e67be88034eb3cd7faffected
LinuxLinux8a800497d9f6c2ec9c2c1ba7b71d0ac2ea7f7bbeaffected
LinuxLinuxde1055e7f9e67af32b1f3376066272b04e5223c0affected
LinuxLinux37ad2bb11e9de92cb7b94548705eeedd87f7d392affected
LinuxLinux8674e2db06cff6b50f2216eed9a761d15425bb34affected
LinuxLinuxce01a4e5cfac7adbe0be565f90cd32ecbb2f8337affected
LinuxLinuxd846d83bdacbd8f14fc45c63b8c1d22608452e1caffected
LinuxLinux5.10.265 < 5.11affected
LinuxLinux5.15.216 < 5.16affected
LinuxLinux6.1.183 < 6.2affected
LinuxLinux6.6.148 < 6.7affected
LinuxLinux6.12.101 < 6.13affected
LinuxLinux6.18.42 < 6.19affected
LinuxLinux7.0.10 < 7.1affected
LinuxLinux7.1affected
LinuxLinux0 < 7.1unaffected
LinuxLinux7.2.7 <= 7.2.*unaffected
LinuxLinux7.3-rc2 <= *unaffected

Weaknesses

References