CVE-2026-43070bpf: Reset register ID for BPF_END value tracking

Official description

In the Linux kernel, the following vulnerability has been resolved: bpf: Reset register ID for BPF_END value tracking When a register undergoes a BPF_END (byte swap) operation, its scalar value is mutated in-place. If this register previously shared a scalar ID with another register (e.g., after an `r1 = r0` assignment), this tie must be broken. Currently, the verifier misses resetting `dst_reg->id` to 0 for BPF_END. Consequently, if a conditional jump checks the swapped register, the verifier incorrectly propagates the learned bounds to the linked register, leading to false confidence in the linked register's value and potentially allowing out-of-bounds memory accesses. Fix this by explicitly resetting `dst_reg->id` to 0 in the BPF_END case to break the scalar tie, similar to how BPF_NEG handles it via `__mark_reg_known`.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/a17443af874229408ce6b78e2c8a2b5adeb4b7d8
• https://git.kernel.org/stable/c/0d15c3611a2cc5d08993545d4032055ae10ae2c1
• https://git.kernel.org/stable/c/a3125bc01884431d30d731461634c8295b6f0529