[Libvirt-cim] [PATCH 2/6] libxkutil:pool_parsing: Coverity cleanups

[Boris Fiuczynski]

On 01/22/2014 08:30 PM, John Ferlan wrote:
> A new version of Coverity found a number of issues:
>
> get_pool_from_xml(): FORWARD_NULL
> parse_disk_pool(): RESOURCE_LEAK
>    - If parse_disk_pool() returned name == NULL, then the strdup() of
>      name into pool->id would dereference the NULL pointer leading to
>      a segfault.
>
>      Furthermore parse_disk_pool() had a few issues.  First the 'type_str'
>      could be NULL, so that needs to be checked.  Second, 'type_str' was
>      never free()'d (the get_attr_value returns a strdup()'d value).
>
>      Realizing all that resulted in a few extra changes to not strdup()
>      a value that we strdup()'d
>
>      Eventually get_pool_from_xml() will return to get_disk_pool() which
>      returns to diskpool_set_capacity() or _new_volume_template() which
>      both error out when return value != 0 (although, I did change the
>      latter to be more explicit and match the former).
>
>      Finally, even though the parsing of the element will only ever have
>      one "name" value - Coverity doesn't know that, so as a benign fix be
>      sure to not overwrite 'name' if "name" isn't already set.
>
> Signed-off-by: John Ferlan <jferlan at redhat.com>
> ---
>   libxkutil/pool_parsing.c              | 39 ++++++++++++++++++-----------------
>   src/Virt_SettingsDefineCapabilities.c |  2 +-
>   2 files changed, 21 insertions(+), 20 deletions(-)
>
> diff --git a/libxkutil/pool_parsing.c b/libxkutil/pool_parsing.c
> index 922ff32..80bd4ca 100644
> --- a/libxkutil/pool_parsing.c
> +++ b/libxkutil/pool_parsing.c
> @@ -194,15 +194,17 @@ char *get_disk_pool_type(uint16_t type)
>
>   }
>
> -static const char *parse_disk_pool(xmlNodeSet *nsv, struct disk_pool *pool)
> +static char *parse_disk_pool(xmlNodeSet *nsv, struct disk_pool *pool)
>   {
>           xmlNode **nodes = nsv->nodeTab;
>           xmlNode *child;
> -        const char *type_str = NULL;
> -        const char *name = NULL;
> +        char *type_str = NULL;
> +        char *name = NULL;
>           int type = 0;
>
>           type_str = get_attr_value(nodes[0], "type");
> +        if (type_str == NULL)
> +            return NULL;
>
>           if (STREQC(type_str, "dir"))
>                   type = DISK_POOL_DIR;
> @@ -220,12 +222,15 @@ static const char *parse_disk_pool(xmlNodeSet *nsv, struct disk_pool *pool)
>                   type = DISK_POOL_SCSI;
>           else
>                   type = DISK_POOL_UNKNOWN;
> +        free(type_str);
>
>           pool->pool_type = type;
> -
> +
>           for (child = nodes[0]->children; child != NULL; child = child->next) {
> -                if (XSTREQ(child->name, "name")) {
> +                if (XSTREQ(child->name, "name") && name == NULL) {
>                           name = get_node_content(child);
> +                        if (name == NULL)
> +                            return NULL;
>                   } else if (XSTREQ(child->name, "target"))
>                           parse_disk_target(child, pool);
>                   else if (XSTREQ(child->name, "source"))
> @@ -238,14 +243,18 @@ static const char *parse_disk_pool(xmlNodeSet *nsv, struct disk_pool *pool)
>   int get_pool_from_xml(const char *xml, struct virt_pool *pool, int type)
>   {
>           int len;
> -        int ret = 0;
> +        int ret = 1;
Isn't this a bug fix... beside a cleanup? Before the return value was 
always 0! It also changes the method get_disk_pool in Virt_DevicePool.c 
in its return value behavior in the same way.
The usage of get_disk_pool in the method diskpool_set_capacity checks 
for the return value and being !=0 it is considered an error 
(Virt_DevicePool.c line 324). Doesn't that need to get changed in this 
patch?
Even so you mention above in your description the two chained 
exploitation code pieces it seems that you fixed just one ... or did I 
miss something?

>           xmlDoc *xmldoc;
>           xmlXPathContext *xpathctx;
>           xmlXPathObject *xpathobj;
>           const xmlChar *xpathstr = (xmlChar *)"/pool";
> -        const char *name;
>
>           CU_DEBUG("Pool XML : %s", xml);
> +
> +        /* FIXME: Add support for parsing network pools */
> +        if (type == CIM_RES_TYPE_NET)
> +                return 0;
> +
>   	len = strlen(xml) + 1;
>
>           if ((xmldoc = xmlParseMemory(xml, len)) == NULL)
> @@ -257,22 +266,14 @@ int get_pool_from_xml(const char *xml, struct virt_pool *pool, int type)
>           if ((xpathobj = xmlXPathEvalExpression(xpathstr, xpathctx)) == NULL)
>                   goto err3;
>
> -        /* FIXME: Add support for parsing network pools */
> -        if (type == CIM_RES_TYPE_NET) {
> -                ret = 0;
> -                goto err1;
> -        }
> -
>           memset(pool, 0, sizeof(*pool));
>
> -        pool->type = CIM_RES_TYPE_DISK;
> -        name = parse_disk_pool(xpathobj->nodesetval,
> -                               &(pool)->pool_info.disk);
> -        if (name == NULL)
> +        pool->type = CIM_RES_TYPE_DISK;
> +        pool->id = parse_disk_pool(xpathobj->nodesetval,
> +                                   &(pool)->pool_info.disk);
> +        if (pool->id != NULL)
>                   ret = 0;
>
> -        pool->id = strdup(name);
> -
>           xmlXPathFreeObject(xpathobj);
>    err3:
>           xmlXPathFreeContext(xpathctx);
> diff --git a/src/Virt_SettingsDefineCapabilities.c b/src/Virt_SettingsDefineCapabilities.c
> index fe16e3f..756e46b 100644
> --- a/src/Virt_SettingsDefineCapabilities.c
> +++ b/src/Virt_SettingsDefineCapabilities.c
> @@ -1376,7 +1376,7 @@ static CMPIStatus _new_volume_template(const CMPIObjectPath *ref,
>           }
>
>           ret = get_disk_pool(poolptr, &pool);
> -        if (ret == 1) {
> +        if (ret != 0) {
>                   virt_set_status(_BROKER, &s,
>                                   CMPI_RC_ERR_FAILED,
>                                   virStoragePoolGetConnect(poolptr),
>
src/Virt_DevicePool.c line 324 =! change seems to be missing.


-- 
Mit freundlichen Grüßen/Kind regards
    Boris Fiuczynski

IBM Deutschland Research & Development GmbH
Vorsitzender des Aufsichtsrats: Martina Köderitz
Geschäftsführung: Dirk Wittkopp
Sitz der Gesellschaft: Böblingen
Registergericht: Amtsgericht Stuttgart, HRB 243294