[libvirt] [PATCH 1/3] storage: Resolve Coverity FORWARD_NULL

[Jiri Denemark]

On Wed, May 13, 2015 at 12:32:20 -0400, John Ferlan wrote:
> Coverity points out it's possible for one of the virCommand{Output|Error}*
> API's to have not allocated 'output' and/or 'error' in which case the
> strstr comparison will cause a NULL deref
> 
> Signed-off-by: John Ferlan <jferlan at redhat.com>
> ---
>  src/storage/storage_backend_disk.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/src/storage/storage_backend_disk.c b/src/storage/storage_backend_disk.c
> index 6394dac..5c2c49a 100644
> --- a/src/storage/storage_backend_disk.c
> +++ b/src/storage/storage_backend_disk.c
> @@ -412,7 +412,7 @@ virStorageBackendDiskFindLabel(const char* device)
>  
>      /* if parted succeeds we have a valid partition table */
>      ret = virCommandRun(cmd, NULL);
> -    if (ret < 0) {
> +    if (ret < 0 && output && error) {
>          if (strstr(output, "unrecognised disk label") ||
>              strstr(error, "unrecognised disk label")) {
>              ret = 1;

This doesn't seem to be correct if either output or error is NULL and
the other one is non-NULL. I'm too lazy to check if it's possible or
not, but I think we should change this code in the following way and be
safe:

    if (ret < 0) {
        if ((output && strstr(output, "unrecognised disk label")) ||
            (error && strstr(error, "unrecognised disk label"))) {
            ret = 1;

Jirka