Re: [Qemu-devel] [PATCH] util/qemu-option: Document the get_opt_value() function

[Damien Hedde]

Hi Philippe,

On 9/19/19 12:49 PM, Philippe Mathieu-Daudé wrote:
> Coverity noticed commit 950c4e6c94 introduced a dereference before
> null check in get_opt_value (CID1391003):
> 
>   In get_opt_value: All paths that lead to this null pointer
>   comparison already dereference the pointer earlier (CWE-476)
> 
> We fixed this in commit 6e3ad3f0e31, but relaxed the check in commit
> 0c2f6e7ee99 because "No callers of get_opt_value() pass in a NULL
> for the 'value' parameter".
> 
> Since this function is publicly exposed, it risks new users to do
> the same error again. Avoid that documenting the 'value' argument
> must not be NULL.
> 
> Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
> ---
>  include/qemu/option.h | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/include/qemu/option.h b/include/qemu/option.h
> index 844587cab3..141d6a883d 100644
> --- a/include/qemu/option.h
> +++ b/include/qemu/option.h
> @@ -28,6 +28,18 @@
>  
>  #include "qemu/queue.h"
>  
> +/**
> + * get_opt_value
> + * @p: a pointer to the option name, delimited by commas
> + * @value: a non-NULL pointer that will received the delimited options
> + *
> + * The @value char pointer will be allocated and filled with
> + * the delimited options.
> + * It is an error to pass a non-NULL @value parameter.

You mean "a NULL @value" I suppose (not a non-NULL).

> + *
> + * Returns the position of the comma delimiter/zero byte after the
> + * option name in @p.
> + */
>  const char *get_opt_value(const char *p, char **value);
>  
>  void parse_option_size(const char *name, const char *value,
> 

--
Damien