Re: [Xen-devel] [PATCH] tools/libxc: Initialise parameters in map_p2m_list() for error paths

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Thu, Jan 07, 2016 at 02:55:30PM +0000, Andrew Cooper wrote:
> c/s 7bf7458 "libxc: support of linear p2m list for migration of
> pv-domains" breaks compilation on CentOS 7 because of 'ptes' being
> possibly uninitialised after the 'err:' label.
> 
> The migration will fail early for conditions which would cause the for()
> loop not to run, but the compiler doesn't know this.
> 
> Initialise the parameters to safe default to make the function more
> robust.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

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

> ---
> CC: Ian Campbell <Ian.Campbell@xxxxxxxxxx>
> CC: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
> CC: Wei Liu <wei.liu2@xxxxxxxxxx>
> CC: Juergen Gross <jgross@xxxxxxxx>
> ---
>  tools/libxc/xc_sr_save_x86_pv.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/libxc/xc_sr_save_x86_pv.c b/tools/libxc/xc_sr_save_x86_pv.c
> index 4deb58f..ab4bbe0 100644
> --- a/tools/libxc/xc_sr_save_x86_pv.c
> +++ b/tools/libxc/xc_sr_save_x86_pv.c
> @@ -316,9 +316,9 @@ static int map_p2m_list(struct xc_sr_context *ctx, 
> uint64_t p2m_cr3)
>      xc_interface *xch = ctx->xch;
>      xen_vaddr_t p2m_vaddr, p2m_end, mask, off;
>      xen_pfn_t p2m_mfn, mfn, saved_mfn, max_pfn;
> -    uint64_t *ptes;
> +    uint64_t *ptes = NULL;
>      xen_pfn_t *mfns;
> -    unsigned fpp, n_pages, level, shift, idx_start, idx_end, idx, saved_idx;
> +    unsigned fpp, n_pages = 0, level, shift, idx_start, idx_end, idx, 
> saved_idx;
>      int rc = -1;
>  
>      p2m_mfn = cr3_to_mfn(ctx, p2m_cr3);
> -- 
> 2.1.4
> 

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