CVE-2026-53090

Summary

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

bpf: Fix ld_{abs,ind} failure path analysis in subprogs

Usage of ld_{abs,ind} instructions got extended into subprogs some time ago via commit 09b28d76eac4 ("bpf: Add abnormal return checks."). These are only allowed in subprograms when the latter are BTF annotated and have scalar return types.

The code generator in bpf_gen_ld_abs() has an abnormal exit path (r0=0 + exit) from legacy cBPF times. While the enforcement is on scalar return types, the verifier must also simulate the path of abnormal exit if the packet data load via ld_{abs,ind} failed.

This is currently not the case. Fix it by having the verifier simulate both success and failure paths, and extend it in similar ways as we do for tail calls. The success path (r0=unknown, continue to next insn) is pushed onto stack for later validation and the r0=0 and return to the caller is done on the fall-through side.

Affected Software

VendorProductVersion RangeStatus
LinuxLinux09b28d76eac48e922dc293da1aa2b2b85c32aeee < d846d83bdacbd8f14fc45c63b8c1d22608452e1caffected
LinuxLinux09b28d76eac48e922dc293da1aa2b2b85c32aeee < ee861486e377edc55361c08dcbceab3f6b6577bdaffected
LinuxLinux5.10affected
LinuxLinux0 < 5.10unaffected
LinuxLinux7.0.10 <= 7.0.*unaffected
LinuxLinux7.1 <= *unaffected

Weaknesses

ADP Enrichment

kernel: bpf: Fix ld_{abs,ind} failure path analysis in subprogs

Additional References

References