From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Cooper <andrew.cooper3@citrix.com>
Subject: Re: [PATCH 08/13 v3] libxl: don't leak ptr in
 libxl_list_vm error case
Date: Mon, 2 Dec 2013 10:35:35 +0000
Message-ID: <529C6277.1060609@citrix.com>
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To: Matthew Daley <mattd@bugfuzz.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>, Ian Jackson <ian.jackson@eu.citrix.com>, Ian Campbell <ian.campbell@citrix.com>, xen-devel@lists.xen.org
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On 02/12/13 02:58, Matthew Daley wrote:
> While at it, tidy up the function; there's no point in allocating more
> than the amount of domains actually returned by xc_domain_getinfolist
> (unless 0 domains are returned, in which case we should still allocate
> one libxl_vminfo struct so we can return a non-NULL result and not
> appear to have failed from the caller's perspective.)
>
> Coverity-ID: 1055888
> Signed-off-by: Matthew Daley <mattd@bugfuzz.com>
> ---
> v3: Oops, min() isn't defined or used anywhere in libxl. Just use a terna=
ry
> expression instead.
>
> v2: Always allocate at least one libxl_vminfo struct for the reason given=
 in
> the commit description.
>
>  tools/libxl/libxl.c |   14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
> index b112294..1a2462c 100644
> --- a/tools/libxl/libxl.c
> +++ b/tools/libxl/libxl.c
> @@ -674,17 +674,17 @@ libxl_vminfo * libxl_list_vm(libxl_ctx *ctx, int *n=
b_vm_out)
>      libxl_vminfo *ptr;
>      int idx, i, ret;
>      xc_domaininfo_t info[1024];
> -    int size =3D 1024;
>  =

> -    ptr =3D calloc(size, sizeof(libxl_vminfo));
> -    if (!ptr)
> +    ret =3D xc_domain_getinfolist(ctx->xch, 1, ARRAY_SIZE(info), info);
> +    if (ret < 0) {
> +        LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, "getting domain info lis=
t");
>          return NULL;
> +    }
>  =

> -    ret =3D xc_domain_getinfolist(ctx->xch, 1, 1024, info);
> -    if (ret<0) {
> -        LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, "geting domain info list=
");
> +    ptr =3D calloc(ret ? ret : 1, sizeof(libxl_vminfo));

Now I reconsider this, a comment in the code wouldn=92t go amis, given the
obscurity.

Also, given -std=3Dgnu99, you can use the gcc-ism of "ret ?: 1"

> +    if (!ptr)
>          return NULL;
> -    }
> +
>      for (idx =3D i =3D 0; i < ret; i++) {
>          if (libxl_is_stubdom(ctx, info[i].domain, NULL))
>              continue;