Re: [Xen-devel] [PATCH] tools: libxl: make it illegal to pass libxl__realloc(gc) a non-gc ptr

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 10/02/16 17:27, Ian Campbell wrote:
> That is, if gc is not NOGC and ptr is not NULL then ptr must be
> associated gc.
>
> Currently in this case the new_ptr would not be registered with any
> gc, which Coverity rightly points out would be a memory leak.
>
> It would also be possible to fix this by adding a libxl__ptr_add() at
> the same point, however semantically it seems like a programming error
> to gc-realloc a pointer which is not associated with the gc in
> question, so treat it as such.
>
> Compile tested only, this change could expose latent bugs.
>
> Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> ---
>  tools/libxl/libxl_internal.c | 7 +++++++
>  tools/libxl/libxl_internal.h | 4 +++-
>  2 files changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/tools/libxl/libxl_internal.c b/tools/libxl/libxl_internal.c
> index 328046b..179d618 100644
> --- a/tools/libxl/libxl_internal.c
> +++ b/tools/libxl/libxl_internal.c
> @@ -122,6 +122,13 @@ void *libxl__realloc(libxl__gc *gc, void *ptr, size_t 
> new_size)
>                  break;
>              }
>          }
> +        /*
> +         * If we get here then ptr was not previously registered with
> +         * this gc.
> +         */
> +        LOG(CRITICAL,
> +            "libxl__realloc on a pointer which tracked by the given gc");

"is not" ?

~Andrew

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