Re: [Xen-devel] [PATCH for-4.5] tools/libxl: Use of init()/dispose() to avoid leaking libxl_dominfo.ssid_label

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Mon, Jan 05, 2015 at 02:19:58PM +0000, Andrew Cooper wrote:
> libxl_dominfo contains a ssid_label pointer which will have memory allocated
> for it in libxl_domain_info() if the hypervisor has CONFIG_XSM compiled.
> However, the lack of appropriate use of libxl_dominfo_{init,dispose}() will
> cause the label string to be leaked, even in success cases.
> 
> This was discovered by XenServers Coverity scanning, and are issues not
> identified by upstream Coverity Scan.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> CC: Ian Campbell <Ian.Campbell@xxxxxxxxxx>
> CC: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>

Reviewed-by : Wei Liu <wei.liu2@xxxxxxxxxx>

> CC: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> 
> ---
> 
> Requesting a release-exception as suggested by IanJ.  These are memory leaks
> which accumulate via the successful completion of libxl library functions (if
> XSM is enabled), which will undoubtedly cause issues for the likes of libvirt
> and xenopsd-libxl which use libxl in daemon processes.
> 
> As we are very close to the release, I have opted for the more
> obviously-correct code rather than the pragmatically better code, particularly
> in two locations where libxl_domain_info() is called in a loop, and the
> dispose()/init() pair is required to prevent leaking the allocation on each
> iteration.
> 
> All of the uses of libxl_domain_info() patched here could better be an
> xc_dominfo_getlist() which reduces the quantity of hypercalls made, and the
> amount of data transformation done behind the scenes.
> ---
>  tools/libxl/libxl.c     |   26 ++++++++++++++++++++++++--
>  tools/libxl/libxl_dom.c |   14 ++++++++++----
>  2 files changed, 34 insertions(+), 6 deletions(-)
> 
> diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
> index 50a8928..372dd3b 100644
> --- a/tools/libxl/libxl.c
> +++ b/tools/libxl/libxl.c
> @@ -364,6 +364,8 @@ int libxl__domain_rename(libxl__gc *gc, uint32_t domid,

(This function is really convoluted. :-/)

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