[libvirt] [PATCH] pci: initialize virtual_functions array pointer to avoid segfault

[Daniel Veillard]

On Mon, Jul 01, 2013 at 12:01:28AM -0400, Laine Stump wrote:
> This fixes https://bugzilla.redhat.com/show_bug.cgi?id=971325
> 
> The problem was that if virPCIGetVirtualFunctions was given the name
> of a non-existent interface, it would return to its caller without
> initializing the pointer to the array of virtual functions to NULL,
> and the caller (virNetDevGetVirtualFunctions) would try to VIR_FREE()
> the invalid pointer.
> 
> The final error message before the crash would be:
> 
>  virPCIGetVirtualFunctions:2088 :
>   Failed to open dir '/sys/class/net/eth2/device':
>   No such file or directory
> 
> In this patch I move the initialization in virPCIGetVirtualFunctions()
> to the begining of the function, and also do an explicit
> initialization in virNetDevGetVirtualFunctions, just in case someone
> in the future adds code into that function prior to the call to
> virPCIGetVirtualFunctions.
> ---
>  src/util/virnetdev.c | 3 +++
>  src/util/virpci.c    | 5 +++--
>  2 files changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/src/util/virnetdev.c b/src/util/virnetdev.c
> index ebe20d0..5e8dffb 100644
> --- a/src/util/virnetdev.c
> +++ b/src/util/virnetdev.c
> @@ -1100,6 +1100,9 @@ virNetDevGetVirtualFunctions(const char *pfname,
>      char *pci_sysfs_device_link = NULL;
>      char *pciConfigAddr = NULL;
>  
> +    *virt_fns = NULL;
> +    *n_vfname = 0;
> +
>      if (virNetDevSysfsFile(&pf_sysfs_device_link, pfname, "device") < 0)
>          return ret;
>  
> diff --git a/src/util/virpci.c b/src/util/virpci.c
> index 2acab1a..15de3f9 100644
> --- a/src/util/virpci.c
> +++ b/src/util/virpci.c
> @@ -2449,6 +2449,9 @@ virPCIGetVirtualFunctions(const char *sysfs_path,
>      VIR_DEBUG("Attempting to get SR IOV virtual functions for device"
>                "with sysfs path '%s'", sysfs_path);
>  
> +    *virtual_functions = NULL;
> +    *num_virtual_functions = 0;
> +
>      dir = opendir(sysfs_path);
>      if (dir == NULL) {
>          memset(errbuf, '\0', sizeof(errbuf));
> @@ -2458,8 +2461,6 @@ virPCIGetVirtualFunctions(const char *sysfs_path,
>          return ret;
>      }
>  
> -    *virtual_functions = NULL;
> -    *num_virtual_functions = 0;
>      while ((entry = readdir(dir))) {
>          if (STRPREFIX(entry->d_name, "virtfn")) {
>              virPCIDeviceAddress *config_addr = NULL;
> -- 
> 1.7.11.7

  ACK,

Daniel

-- 
Daniel Veillard      | Open Source and Standards, Red Hat
veillard at redhat.com  | libxml Gnome XML XSLT toolkit  http://xmlsoft.org/
http://veillard.com/ | virtualization library  http://libvirt.org/