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Re: [libvirt] [PATCH] xen_hypervisor.c: avoid NULL deref for NULL domain argument



On Wed, Jan 27, 2010 at 01:39:13PM +0100, Jim Meyering wrote:
> Daniel P. Berrange wrote:
> > On Tue, Jan 26, 2010 at 08:24:25PM +0100, Jim Meyering wrote:
> >> When "domain" is NULL, don't deref NULL.  Instead, just return -1,
> >> as in many other functions in this file, and as this function did
> >> up until a month ago.
> >>
> >> An alternative (taken 3 times in this file) is to do this:
> >>
> >>         virXenErrorFunc (NULL, VIR_ERR_INTERNAL_ERROR, __FUNCTION__,
> >>                          "domain or conn is NULL", 0);
> >>         return -1;
> >>
> >> I could go either way.
> >>
> >>
> >> >From 177556167775b806a29bcb1af7ba4294d1909912 Mon Sep 17 00:00:00 2001
> >> From: Jim Meyering <meyering redhat com>
> >> Date: Tue, 26 Jan 2010 20:17:07 +0100
> >> Subject: [PATCH] xen_hypervisor.c: avoid NULL deref for NULL domain argument
> >>
> >> * src/xen/xen_hypervisor.c (xenHypervisorGetVcpus): Don't attempt
> >> to diagnose an unlikely NULL-domain or NULL-domain->conn error.
> >> ---
> >>  src/xen/xen_hypervisor.c |    7 ++-----
> >>  1 files changed, 2 insertions(+), 5 deletions(-)
> >>
> >> diff --git a/src/xen/xen_hypervisor.c b/src/xen/xen_hypervisor.c
> >> index 6d8accc..0257be2 100644
> >> --- a/src/xen/xen_hypervisor.c
> >> +++ b/src/xen/xen_hypervisor.c
> >> @@ -1,7 +1,7 @@
> >>  /*
> >>   * xen_internal.c: direct access to Xen hypervisor level
> >>   *
> >> - * Copyright (C) 2005, 2006, 2007, 2008, 2009 Red Hat, Inc.
> >> + * Copyright (C) 2005-2010 Red Hat, Inc.
> >>   *
> >>   * See COPYING.LIB for the License of this software
> >>   *
> >> @@ -3475,11 +3475,8 @@ xenHypervisorGetVcpus(virDomainPtr domain, virVcpuInfoPtr info, int maxinfo,
> >>      virVcpuInfoPtr ipt;
> >>      int nbinfo, i;
> >>
> >> -    if (domain == NULL || domain->conn == NULL) {
> >> -        virXenErrorFunc (domain->conn, VIR_ERR_INVALID_ARG, __FUNCTION__,
> >> -                        "invalid argument", 0);
> >> +    if (domain == NULL || domain->conn == NULL)
> >>          return -1;
> >> -    }
> >
> > I'd rather we just got rid of that check completely - its a left
> > over from a time when Xen was the only driver & these entry points
> > needed to do full checking. Now all mandatory parameters are checked
> > in the previous libvirt.c layer.
> 
> Here's an additional patch, to eliminate all of the "domain == NULL"
> tests.  I want to keep this global "clean-up" patch separate from
> the above bug-fixing one.
> 
> I'm less confident about removing the daomin->conn tests,
> and would be inclined to leave them as-is, or use an assert, if you
> want to remove them.  If we also remove the daomin->conn == NULL tests,
> an added "assert" is the best way to keep clang/coverity from
> complaining about a possible NULL-dereference.
> 
> From 9e6f7ca7a0dfa6b220e598d04ca40d33e67feb22 Mon Sep 17 00:00:00 2001
> From: Jim Meyering <meyering redhat com>
> Date: Wed, 27 Jan 2010 13:34:03 +0100
> Subject: [PATCH] xen_hypervisor.c: remove all "domain == NULL" tests, ...
> 
> * src/xen/xen_hypervisor.c: Remove all "domain == NULL" tests.
> * src/xen/xen_hypervisor.h: Instead, use ATTRIBUTE_NONNULL to
> mark each "domain" parameter as "known always to be non-NULL".
> ---
>  src/xen/xen_hypervisor.c |   28 ++++++++++++++--------------
>  src/xen/xen_hypervisor.h |   44 +++++++++++++++++++++++++++++---------------
>  2 files changed, 43 insertions(+), 29 deletions(-)
> 
> diff --git a/src/xen/xen_hypervisor.c b/src/xen/xen_hypervisor.c
> index 0257be2..994f5ef 100644
> --- a/src/xen/xen_hypervisor.c
> +++ b/src/xen/xen_hypervisor.c
> @@ -1130,7 +1130,7 @@ xenHypervisorGetSchedulerType(virDomainPtr domain, int *nparams)
>      char *schedulertype = NULL;
>      xenUnifiedPrivatePtr priv;
> 
> -    if ((domain == NULL) || (domain->conn == NULL)) {
> +    if (domain->conn == NULL) {
>          virXenErrorFunc(NULL, VIR_ERR_INTERNAL_ERROR, __FUNCTION__,
>                          "domain or conn is NULL", 0);
>          return NULL;
> @@ -1214,7 +1214,7 @@ xenHypervisorGetSchedulerParameters(virDomainPtr domain,
>  {
>      xenUnifiedPrivatePtr priv;
> 
> -    if ((domain == NULL) || (domain->conn == NULL)) {
> +    if (domain->conn == NULL) {
>          virXenErrorFunc(NULL, VIR_ERR_INTERNAL_ERROR, __FUNCTION__,
>                          "domain or conn is NULL", 0);
>          return -1;
> @@ -1317,7 +1317,7 @@ xenHypervisorSetSchedulerParameters(virDomainPtr domain,
>      xenUnifiedPrivatePtr priv;
>      char buf[256];
> 
> -    if ((domain == NULL) || (domain->conn == NULL)) {
> +    if (domain->conn == NULL) {
>          virXenErrorFunc (NULL, VIR_ERR_INTERNAL_ERROR, __FUNCTION__,
>                           "domain or conn is NULL", 0);
>          return -1;
> @@ -3062,12 +3062,12 @@ xenHypervisorGetDomMaxMemory(virConnectPtr conn, int id)
>   *
>   * Returns the memory size in kilobytes or 0 in case of error.
>   */
> -static unsigned long
> +static unsigned long ATTRIBUTE_NONNULL (1)
>  xenHypervisorGetMaxMemory(virDomainPtr domain)
>  {
>      xenUnifiedPrivatePtr priv;
> 
> -    if ((domain == NULL) || (domain->conn == NULL))
> +    if (domain->conn == NULL)
>          return 0;
> 
>      priv = (xenUnifiedPrivatePtr) domain->conn->privateData;
> @@ -3176,7 +3176,7 @@ xenHypervisorGetDomainInfo(virDomainPtr domain, virDomainInfoPtr info)
>  {
>      xenUnifiedPrivatePtr priv;
> 
> -    if ((domain == NULL) || (domain->conn == NULL))
> +    if (domain->conn == NULL)
>          return -1;
> 
>      priv = (xenUnifiedPrivatePtr) domain->conn->privateData;
> @@ -3284,7 +3284,7 @@ xenHypervisorPauseDomain(virDomainPtr domain)
>      int ret;
>      xenUnifiedPrivatePtr priv;
> 
> -    if ((domain == NULL) || (domain->conn == NULL))
> +    if (domain->conn == NULL)
>          return -1;
> 
>      priv = (xenUnifiedPrivatePtr) domain->conn->privateData;
> @@ -3311,7 +3311,7 @@ xenHypervisorResumeDomain(virDomainPtr domain)
>      int ret;
>      xenUnifiedPrivatePtr priv;
> 
> -    if ((domain == NULL) || (domain->conn == NULL))
> +    if (domain->conn == NULL)
>          return -1;
> 
>      priv = (xenUnifiedPrivatePtr) domain->conn->privateData;
> @@ -3338,7 +3338,7 @@ xenHypervisorDestroyDomain(virDomainPtr domain)
>      int ret;
>      xenUnifiedPrivatePtr priv;
> 
> -    if (domain == NULL || domain->conn == NULL)
> +    if (domain->conn == NULL)
>          return -1;
> 
>      priv = (xenUnifiedPrivatePtr) domain->conn->privateData;
> @@ -3366,7 +3366,7 @@ xenHypervisorSetMaxMemory(virDomainPtr domain, unsigned long memory)
>      int ret;
>      xenUnifiedPrivatePtr priv;
> 
> -    if (domain == NULL || domain->conn == NULL)
> +    if (domain->conn == NULL)
>          return -1;
> 
>      priv = (xenUnifiedPrivatePtr) domain->conn->privateData;
> @@ -3397,7 +3397,7 @@ xenHypervisorSetVcpus(virDomainPtr domain, unsigned int nvcpus)
>      int ret;
>      xenUnifiedPrivatePtr priv;
> 
> -    if (domain == NULL || domain->conn == NULL)
> +    if (domain->conn == NULL)
>          return -1;
> 
>      priv = (xenUnifiedPrivatePtr) domain->conn->privateData;
> @@ -3429,7 +3429,7 @@ xenHypervisorPinVcpu(virDomainPtr domain, unsigned int vcpu,
>      int ret;
>      xenUnifiedPrivatePtr priv;
> 
> -    if (domain == NULL || domain->conn == NULL)
> +    if (domain->conn == NULL)
>          return -1;
> 
>      priv = (xenUnifiedPrivatePtr) domain->conn->privateData;
> @@ -3475,7 +3475,7 @@ xenHypervisorGetVcpus(virDomainPtr domain, virVcpuInfoPtr info, int maxinfo,
>      virVcpuInfoPtr ipt;
>      int nbinfo, i;
> 
> -    if (domain == NULL || domain->conn == NULL)
> +    if (domain->conn == NULL)
>          return -1;
> 
>      priv = (xenUnifiedPrivatePtr) domain->conn->privateData;
> @@ -3548,7 +3548,7 @@ xenHypervisorGetVcpuMax(virDomainPtr domain)
>      int maxcpu;
>      xenUnifiedPrivatePtr priv;
> 
> -    if (domain == NULL || domain->conn == NULL)
> +    if (domain->conn == NULL)
>          return -1;
> 
>      priv = (xenUnifiedPrivatePtr) domain->conn->privateData;
> diff --git a/src/xen/xen_hypervisor.h b/src/xen/xen_hypervisor.h
> index 5971a90..4504733 100644
> --- a/src/xen/xen_hypervisor.h
> +++ b/src/xen/xen_hypervisor.h
> @@ -1,7 +1,7 @@
>  /*
>   * xen_internal.h: internal API for direct access to Xen hypervisor level
>   *
> - * Copyright (C) 2005 Red Hat, Inc.
> + * Copyright (C) 2005, 2010 Red Hat, Inc.
>   *
>   * See COPYING.LIB for the License of this software
>   *
> @@ -58,48 +58,62 @@ int     xenHypervisorListDomains        (virConnectPtr conn,
>                                           int maxids);
>  int     xenHypervisorGetMaxVcpus        (virConnectPtr conn,
>                                           const char *type);
> -int     xenHypervisorDestroyDomain      (virDomainPtr domain);
> -int     xenHypervisorResumeDomain       (virDomainPtr domain);
> -int     xenHypervisorPauseDomain        (virDomainPtr domain);
> +int     xenHypervisorDestroyDomain      (virDomainPtr domain)
> +          ATTRIBUTE_NONNULL (1);
> +int     xenHypervisorResumeDomain       (virDomainPtr domain)
> +          ATTRIBUTE_NONNULL (1);
> +int     xenHypervisorPauseDomain        (virDomainPtr domain)
> +          ATTRIBUTE_NONNULL (1);
>  int     xenHypervisorGetDomainInfo        (virDomainPtr domain,
> -                                         virDomainInfoPtr info);
> +                                           virDomainInfoPtr info)
> +          ATTRIBUTE_NONNULL (1);
>  int     xenHypervisorGetDomInfo         (virConnectPtr conn,
>                                           int id,
>                                           virDomainInfoPtr info);
>  int     xenHypervisorSetMaxMemory       (virDomainPtr domain,
> -                                         unsigned long memory);
> +                                         unsigned long memory)
> +          ATTRIBUTE_NONNULL (1);
>  int     xenHypervisorCheckID            (virConnectPtr conn,
>                                           int id);
>  int     xenHypervisorSetVcpus           (virDomainPtr domain,
> -                                         unsigned int nvcpus);
> +                                         unsigned int nvcpus)
> +          ATTRIBUTE_NONNULL (1);
>  int     xenHypervisorPinVcpu            (virDomainPtr domain,
>                                           unsigned int vcpu,
>                                           unsigned char *cpumap,
> -                                         int maplen);
> +                                         int maplen)
> +          ATTRIBUTE_NONNULL (1);
>  int     xenHypervisorGetVcpus           (virDomainPtr domain,
>                                           virVcpuInfoPtr info,
>                                           int maxinfo,
>                                           unsigned char *cpumaps,
> -                                         int maplen);
> -int     xenHypervisorGetVcpuMax         (virDomainPtr domain);
> +                                         int maplen)
> +          ATTRIBUTE_NONNULL (1);
> +int     xenHypervisorGetVcpuMax         (virDomainPtr domain)
> +          ATTRIBUTE_NONNULL (1);
> 
>  char *  xenHypervisorGetSchedulerType   (virDomainPtr domain,
> -                                         int *nparams);
> +                                         int *nparams)
> +          ATTRIBUTE_NONNULL (1);
> 
>  int     xenHypervisorGetSchedulerParameters(virDomainPtr domain,
>                                           virSchedParameterPtr params,
> -                                         int *nparams);
> +                                         int *nparams)
> +          ATTRIBUTE_NONNULL (1);
> 
>  int     xenHypervisorSetSchedulerParameters(virDomainPtr domain,
>                                           virSchedParameterPtr params,
> -                                         int nparams);
> +                                         int nparams)
> +          ATTRIBUTE_NONNULL (1);
> 
>  int     xenHypervisorDomainBlockStats   (virDomainPtr domain,
>                                           const char *path,
> -                                         struct _virDomainBlockStats *stats);
> +                                         struct _virDomainBlockStats *stats)
> +          ATTRIBUTE_NONNULL (1);
>  int     xenHypervisorDomainInterfaceStats (virDomainPtr domain,
>                                           const char *path,
> -                                         struct _virDomainInterfaceStats *stats);
> +                                         struct _virDomainInterfaceStats *stats)
> +          ATTRIBUTE_NONNULL (1);
> 
>  int     xenHypervisorNodeGetCellsFreeMemory(virConnectPtr conn,
>                                            unsigned long long *freeMems,
> --

ACK

Daniel
-- 
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