Re: [PATCH] Fix stubdom build failure for RELEASE-4.3.1

[Andrew Cooper <andrew.cooper3@citrix.com>]

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On 31/10/13 14:44, Alex Sharp wrote:
> Hey,
>
> I noticed that RELEASE-4.3.1 (commit
> 4e8e0bdef96859e6f428af74be6f4a3bc7fd11f3) was failing to make stubdom,
> complaining of various forms of format string mismatch. The following
> patch at least gets things to compile, but I'm not sure if there's a
> deeper underlying issue. I'm using gcc version 4.8.1 (Ubuntu/Linaro
> 4.8.1-10ubuntu8) on x86_64. My .config contains the line
> "PYTHON_PREFIX_ARG=--install-layout=deb" and I'm ./configuring with
> --prefix=
>
> Hope this helps.
>
> diff --git a/extras/mini-os/fbfront.c b/extras/mini-os/fbfront.c
> index 54a5e67..b6aaa6b 100644
> --- a/extras/mini-os/fbfront.c
> +++ b/extras/mini-os/fbfront.c
> @@ -105,7 +105,7 @@ again:
>          free(err);
>      }
>  
> -    err = xenbus_printf(xbt, nodename, "page-ref","%u", virt_to_mfn(s));
> +    err = xenbus_printf(xbt, nodename, "page-ref","%lu", virt_to_mfn(s));
>      if (err) {
>          message = "writing page-ref";
>          goto abort_transaction;
> @@ -463,7 +463,7 @@ again:
>          free(err);
>      }
>  
> -    err = xenbus_printf(xbt, nodename, "page-ref","%u", virt_to_mfn(s));
> +    err = xenbus_printf(xbt, nodename, "page-ref","%lu", virt_to_mfn(s));

The two above here are certainly valid.  virt_to_mfn() goes through many
macros and ends up reading out of "unsigned long *phys_to_machine_mapping".

>      if (err) {
>          message = "writing page-ref";
>          goto abort_transaction;
> diff --git a/extras/mini-os/pcifront.c b/extras/mini-os/pcifront.c
> index bbe21e0..9d0cb17 100644
> --- a/extras/mini-os/pcifront.c
> +++ b/extras/mini-os/pcifront.c
> @@ -413,7 +413,7 @@ int pcifront_physical_to_virtual (struct
> pcifront_dev *dev,
>                  continue;
>              }
>  
> -            if (sscanf(s, "%x:%x:%x.%x", dom, bus, slot, fun) != 4) {
> +            if (sscanf(s, "%x:%x:%x.%lx", dom, bus, slot, fun) != 4) {

This is a little awkward.  It has been changed in unstable and is now
correct.  Perhaps a subset of the change needs backporting

>                  printk("\"%s\" does not look like a PCI device
> address\n", s);
>                  free(s);
>                  continue;
> diff --git a/extras/mini-os/xenbus/xenbus.c
> b/extras/mini-os/xenbus/xenbus.c
> index ee1691b..fa2e872 100644
> --- a/extras/mini-os/xenbus/xenbus.c
> +++ b/extras/mini-os/xenbus/xenbus.c
> @@ -672,7 +672,7 @@ char
> *xenbus_transaction_start(xenbus_transaction_t *xbt)
>      err = errmsg(rep);
>      if (err)
>         return err;
> -    sscanf((char *)(rep + 1), "%u", xbt);
> +    sscanf((char *)(rep + 1), "%lu", xbt);

This is good

>      free(rep);
>      return NULL;
>  }
> @@ -769,7 +769,7 @@ domid_t xenbus_get_self_id(void)
>      domid_t ret;
>  
>      BUG_ON(xenbus_read(XBT_NIL, "domid", &dom_id));
> -    sscanf(dom_id, "%d", &ret);
> +    sscanf(dom_id, "%u", (unsigned int*)&ret);

This needs to be

sscanf(dom_id, "%"SCNd16, &ret);

That pointer casting there will result in stack corruption.

Could you please follow the instructions
http://wiki.xen.org/wiki/Submitting_Xen_Patches (specifically the
Signed-off-by line) and submit a patch against xen-unstable, which can
then be backported appropriately.

~Andrew

>  
>      return ret;
>  }
>
>
>
> _______________________________________________
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> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel


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