PT-2026-51975 · Linux · Linux
Published
2026-06-24
·
Updated
2026-06-24
·
CVE-2026-53081
None
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In 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.
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Related Identifiers
Affected Products
Linux