On Thu, Jun 02, 2016 at 12:42:52 +0200, Michal Privoznik wrote:
> There's this problem on the recent gcc-6.1:
>
> 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++) {
> ^~~~~~~
>
> GCC basically fails to see, that the
> virDomainChrGetDomainPtrsInternal will never actually return NULL
> because it's never called over a domain char device with _LAST
> type. But to make it shut up, lets turn this function into
> returning an integer and check in the callers if a zero value
> value was returned.
>
> Signed-off-by: Michal Privoznik <mprivozn@xxxxxxxxxx>
> ---
> src/conf/domain_conf.c | 27 +++++++++++++++++----------
> 1 file changed, 17 insertions(+), 10 deletions(-)
>
> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
> index 568c699..2efe0a3 100644
> --- a/src/conf/domain_conf.c
> +++ b/src/conf/domain_conf.c
> @@ -14038,7 +14038,7 @@ virDomainChrFind(virDomainDefPtr def,
>
> /* Return the address within vmdef to be modified when working with a
> * chrdefptr of the given type. */
> -static void
> +static int ATTRIBUTE_RETURN_CHECK
> virDomainChrGetDomainPtrsInternal(virDomainDefPtr vmdef,
> virDomainChrDeviceType type,
> virDomainChrDefPtr ***arrPtr,
> @@ -14070,6 +14070,8 @@ virDomainChrGetDomainPtrsInternal(virDomainDefPtr vmdef,
> *cntPtr = NULL;
> break;
> }
> +
> + return (*arrPtr && *cntPtr) ? 0 : -1;
This doesn't set any error. The VIR_DOMAIN_CHR_DEVICE_TYPE_LAST case
should do so and possibly return -1 right away to avoid the ternary.
> }
>
[...]
> @@ -14104,7 +14105,9 @@ virDomainChrPreAlloc(virDomainDefPtr vmdef,
> virDomainChrDefPtr **arrPtr = NULL;
> size_t *cntPtr = NULL;
>
> - virDomainChrGetDomainPtrsInternal(vmdef, chr->deviceType, &arrPtr, &cntPtr);
> + if (virDomainChrGetDomainPtrsInternal(vmdef, chr->deviceType,
> + &arrPtr, &cntPtr) < 0)
> + return -1;
So this will report the "unknown error".
>
> return VIR_REALLOC_N(*arrPtr, *cntPtr + 1);
ACK with the error added.
--
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