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KERN_SUCCESS
KERN_SUCCESS is zero in the kern_return_t namespace and reports successful completion of the Mach kernel interface that returned it. Callers must still validate the output counts, returned rights, and object state defined by that specific routine.
Operational meaning
KERN_SUCCESS is not a universal success token for POSIX, IOKit, or Mach messaging. A zero integer returned through errno, IOReturn, or mach_msg_return_t belongs to a different contract even when its bit pattern is identical.
Build a reproducible record
| Capture | Diagnostic value |
|---|---|
| The MIG routine or Mach kernel call, its subsystem interface, and the exact kern_return_t value. | Identifies the concrete object and operation associated with successful Mach kernel primitive. |
| Input and output port names together with the right types held before and after the call. | Separates argument or lifecycle state from the provider beneath successful Mach kernel primitive. |
| Returned counts, flavor selectors, structure versions, and buffer sizes used by the routine. | Confirms that counts, selectors, structure versions, and buffer sizes belong to the same successful call. |
| Task, thread, host, or memory-object identity and the lifecycle event immediately following success. | Shows whether KERN_SUCCESS is the first result or a translated summary. |
Checks that separate the causes
- Repeat the routine with one intentionally invalid right or flavor and verify a nonzero kern_return_t is returned.
- Validate the output count before reading variable-length data supplied by the kernel.
- Deallocate or transfer every returned Mach right according to the routine contract and check for right leaks.
Resolution criteria
Targeted correction. Preserve the routine-specific validation and ownership checks after it instead of collapsing every zero kern_return_t into one generic success path.
Acceptance criterion. The Mach routine returns it, all output counts and rights match the interface definition, and repeated execution leaves no leaked or unexpectedly consumed rights.
Technical references
- Apple XNU: kern_return_t definitions — defines the status namespace used.
- Apple: Mach overview — documents the API or lifecycle boundary behind it.
- Apple XNU source repository — provides ABI, implementation, or protocol context.
- Apple XNU: Mach message definitions — supports the portability and verification limits.
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