bpf: Enforce regsafe base id consistency for BPF_ADD_CONST scalars

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Summary

CVECVE-2026-53081
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-24 17:17:22 UTC
Updated2026-06-24 17:17:22 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: bpf: Enforce regsafe base id consistency for BPF_ADD_CONST scalars When regsafe() compares two scalar registers that both carry BPF_ADD_CONST, check_scalar_ids() maps their full compound id (aka base | BPF_ADD_CONST flag) as one idmap entry. However, it never verifies that the underlying base ids, that is, with the flag stripped are consistent with existing idmap mappings. This allows construction of two verifier states where the old state has R3 = R2 + 10 (both sharing base id A) while the current state has R3 = R4 + 10 (base id C, unrelated to R2). The idmap creates two independent entries: A->B (for R2) and A|flag->C|flag (for R3), without catching that A->C conflicts with A->B. State pruning then incorrectly succeeds. Fix this by additionally verifying base ID mapping consistency whenever BPF_ADD_CONST is set: after mapping the compound ids, also invoke check_ids() on the base IDs (flag bits stripped). This ensures that if A was already mapped to B from comparing the source register, any ADD_CONST derivative must also derive from B, not an unrelated C.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 98d7ca374ba4b39e7535613d40e159f09ca14da2 13c02881e49aac4c82b261faa26db9edf2567231 git Not specified
CNA Linux Linux affected 98d7ca374ba4b39e7535613d40e159f09ca14da2 691adf738817275368ed56311b7d798d617823a3 git Not specified
CNA Linux Linux affected 98d7ca374ba4b39e7535613d40e159f09ca14da2 7d73c72cccac651acc891377a5e623e4021c6380 git Not specified
CNA Linux Linux affected 98d7ca374ba4b39e7535613d40e159f09ca14da2 2f2ec8e7730e21fc9bd49e0de9cdd58213ea24d0 git Not specified
CNA Linux Linux affected 6.11 Not specified
CNA Linux Linux unaffected 6.11 semver Not specified
CNA Linux Linux unaffected 6.12.91 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.33 6.18.* semver Not specified
CNA Linux Linux unaffected 7.0.10 7.0.* semver Not specified
CNA Linux Linux unaffected 7.1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/691adf738817275368ed56311b7d798d617823a3 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/2f2ec8e7730e21fc9bd49e0de9cdd58213ea24d0 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/13c02881e49aac4c82b261faa26db9edf2567231 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/7d73c72cccac651acc891377a5e623e4021c6380 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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