[libvirt] [PATCH 6/6] domain_conf: Avoid false positive

[Peter Krempa]

On Tue, May 31, 2016 at 12:33:33 +0200, Michal Privoznik wrote:
> Gcc fails to see that virDomainChrGetDomainPtrsInternal always
> sets pointers to a non NULL value (except for
> chr device type VIR_DOMAIN_CHR_DEVICE_TYPE_LAST which if occurs,
> we are in way bigger problem than NULL deref).
> 
> In file included from conf/domain_conf.c:37:0:
> conf/domain_conf.c: In function 'virDomainChrPreAlloc':
> conf/domain_conf.c:14109:35: error: potential null pointer dereference [-Werror=null-dereference]
>      return VIR_REALLOC_N(*arrPtr, *cntPtr + 1);
>                                    ^~
> ./util/viralloc.h:158:73: note: in definition of macro 'VIR_REALLOC_N'
>  # define VIR_REALLOC_N(ptr, count) virReallocN(&(ptr), sizeof(*(ptr)), (count), \
>                                                                          ^~~~~
> conf/domain_conf.c: In function 'virDomainChrRemove':
> conf/domain_conf.c:14133:21: error: potential null pointer dereference [-Werror=null-dereference]
>      for (i = 0; i < *cntPtr; i++) {
>                      ^~~~~~~
> cc1: all warnings being treated as errors
> 
> Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
> ---
>  src/conf/domain_conf.c | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 
> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
> index 3daeb1e..67ed4d7 100644
> --- a/src/conf/domain_conf.c
> +++ b/src/conf/domain_conf.c
> @@ -14106,6 +14106,12 @@ virDomainChrPreAlloc(virDomainDefPtr vmdef,
>  
>      virDomainChrGetDomainPtrsInternal(vmdef, chr->deviceType, &arrPtr, &cntPtr);
>  
> +    if (!arrPtr || !cntPtr) {
> +        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> +                       _("Impossible happened"));
> +        return -1;
> +    }
> +
>      return VIR_REALLOC_N(*arrPtr, *cntPtr + 1);
>  }

NACK
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