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.