CVE-2026-98034

Summary

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

bpf: Mark NULL kptr stores precise

check_map_kptr_access() permits a scalar store into an untrusted kptr field only when the register is known to contain zero. Unlike other verifier checks whose outcome depends on a scalar value, it does not mark that register precise.

A state checkpoint reached with an imprecise zero can therefore prune a second path that reaches the store with an arbitrary nonzero scalar. The program can write attacker-controlled bits into the kptr field and load them back as a PTR_TO_BTF_ID.

Call mark_chain_precision() before accepting a known-zero register. This forces state equivalence to compare its scalar range and makes the verifier visit and reject a path carrying a nonzero value.

Affected Software

VendorProductVersion RangeStatus
LinuxLinux61df10c7799e27807ad5e459eec9d77cddf8bf45 < 86168208737bdd267d92d855d453d1d2f840df19affected
LinuxLinux61df10c7799e27807ad5e459eec9d77cddf8bf45 < ecdc5043794c9184aa8e6c814603899479c46b35affected
LinuxLinuxb5a8069835e5236824a84281592d29f859b33153affected
LinuxLinux5.18.18 < 5.19affected
LinuxLinux5.19affected
LinuxLinux0 < 5.19unaffected
LinuxLinux7.2.7 <= 7.2.*unaffected
LinuxLinux7.3-rc2 <= *unaffected

Weaknesses

References