Re: [Qemu-devel] [PATCH v5 2/5] Add Error **errp for xen_host_pci_device_get()

[Eric Blake]

On 01/13/2016 05:51 AM, Cao jin wrote:
> To catch the error msg. Also modify the caller
> 
> Signed-off-by: Cao jin <address@hidden>
> ---
>  hw/xen/xen-host-pci-device.c | 142 
> +++++++++++++++++++++----------------------
>  hw/xen/xen-host-pci-device.h |   5 +-
>  hw/xen/xen_pt.c              |  13 ++--
>  3 files changed, 80 insertions(+), 80 deletions(-)
> 
> diff --git a/hw/xen/xen-host-pci-device.c b/hw/xen/xen-host-pci-device.c
> index 351b61a..3e22de8 100644
> --- a/hw/xen/xen-host-pci-device.c
> +++ b/hw/xen/xen-host-pci-device.c
> @@ -31,25 +31,20 @@
>  #define IORESOURCE_PREFETCH     0x00001000      /* No side effects */
>  #define IORESOURCE_MEM_64       0x00100000
>  
> -static int xen_host_pci_sysfs_path(const XenHostPCIDevice *d,
> -                                   const char *name, char *buf, ssize_t size)
> +static void xen_host_pci_sysfs_path(const XenHostPCIDevice *d,
> +                                    const char *name, char *buf, ssize_t 
> size)

Changing xen_host_pci_sysfs_path() to return void, by assert()ing on
caller error, is not mentioned in the commit message; and if I were
doing the series, I probably would have done it as a separate commit.

>  /* This size should be enough to read a long from a file */
>  #define XEN_HOST_PCI_GET_VALUE_BUFFER_SIZE 22
> -static int xen_host_pci_get_value(XenHostPCIDevice *d, const char *name,
> -                                  unsigned int *pvalue, int base)
> +static void xen_host_pci_get_value(XenHostPCIDevice *d, const char *name,
> +                                   unsigned int *pvalue, int base, Error 
> **errp)
>  {

>      buf[rc] = 0;
> -    rc = qemu_strtoul(buf, &endptr, base, &value);
> -    if (!rc) {
> -        *pvalue = value;
> +    rc = qemu_strtoul(buf, &endptr, base, (unsigned long *)pvalue);

Ouch. Casting unsigned int * to unsigned long * and then dereferencing
it is bogus (you end up having qemu_strtoul() write beyond bounds on
platforms where long is larger than int).  You'll need to revert this
part of the patch, and stick with *pvalue = value (and possibly even add
a bounds check that value <= UINT_MAX).

Otherwise looks okay.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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