Re: [Qemu-devel] [PATCH v3 2/8] job: Fix off-by-one assert checks for JobSTT and JobVerbTable

[John Snow]

On 08/31/2018 02:16 PM, Liam Merwick wrote:
> In the assert checking the array dereference of JobVerbTable[verb]
> in job_apply_verb() the check of the index, verb, allows an overrun
> because an index equal to the array size is permitted.
> 
> Similarly, in the assert check of JobSTT[s0][s1] with index s1
> in job_state_transition(), an off-by-one overrun is not flagged
> either.
> 

Oops.

> This is not a run-time issue as there are no callers actually
> passing in the max value.
> 

Good.

> Signed-off-by: Liam Merwick <address@hidden>
> Reviewed-by: Darren Kenny <address@hidden>
> Reviewed-by: Mark Kanda <address@hidden>
> Reviewed-by: Eric Blake <address@hidden>

Reviewed-by: John Snow <address@hidden>

> ---
>  job.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/job.c b/job.c
> index e36ebaafd81c..40320566f43b 100644
> --- a/job.c
> +++ b/job.c
> @@ -166,7 +166,7 @@ bool job_is_internal(Job *job)
>  static void job_state_transition(Job *job, JobStatus s1)
>  {
>      JobStatus s0 = job->status;
> -    assert(s1 >= 0 && s1 <= JOB_STATUS__MAX);
> +    assert(s1 >= 0 && s1 < JOB_STATUS__MAX);
>      trace_job_state_transition(job, job->ret,
>                                 JobSTT[s0][s1] ? "allowed" : "disallowed",
>                                 JobStatus_str(s0), JobStatus_str(s1));
> @@ -181,7 +181,7 @@ static void job_state_transition(Job *job, JobStatus s1)
>  int job_apply_verb(Job *job, JobVerb verb, Error **errp)
>  {
>      JobStatus s0 = job->status;
> -    assert(verb >= 0 && verb <= JOB_VERB__MAX);
> +    assert(verb >= 0 && verb < JOB_VERB__MAX);
>      trace_job_apply_verb(job, JobStatus_str(s0), JobVerb_str(verb),
>                           JobVerbTable[verb][s0] ? "allowed" : "prohibited");
>      if (JobVerbTable[verb][s0]) {
>