Re: [Xen-devel] [PATCH for-4.10] libxl: handle NULL in libxl__enum_from_string

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Fri, Oct 13, 2017 at 01:46:57PM +0100, Ian Jackson wrote:
> Wei Liu writes ("[PATCH for-4.10] libxl: handle NULL in 
> libxl__enum_from_string"):
> > Discovered by Coverity.
> 
> But.  Surely it is very wrong
> 
> > @@ -1017,7 +1017,7 @@ int libxl_get_max_nodes(libxl_ctx *ctx)
> >  int libxl__enum_from_string(const libxl_enum_string_table *t,
> >                              const char *s, int *e)
> >  {
> > -    if (!t) return ERROR_INVAL;
> > +    if (!t || !s) return ERROR_INVAL;
> 
> to call this function with s==NULL.
> 
> I'm not generally in favour of turning such mistakes from
> easy-to-debug crashes into hard-to-track-down error codes (especially
> with our nonspecific error codes).
> 
> Where does that occur ?
> 

libxl_*_type_from_string.

I agree they shouldn't be called with NULL. We should guard against
error (here or the libxl_*_type_from_string) or annotate the input can't
be NULL.

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