| Message ID | 20240223085653.1255438-6-zhao1.liu@linux.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Cleanup and fix @errp dereference | expand |
On Fri, 23 Feb 2024 16:56:51 +0800 Zhao Liu <zhao1.liu@linux.intel.com> wrote: > From: Zhao Liu <zhao1.liu@intel.com> > > As the comment in qapi/error, dereferencing @errp requires > ERRP_GUARD(): > > * = Why, when and how to use ERRP_GUARD() = > * > * Without ERRP_GUARD(), use of the @errp parameter is restricted: > * - It must not be dereferenced, because it may be null. > ... > * ERRP_GUARD() lifts these restrictions. > * > * To use ERRP_GUARD(), add it right at the beginning of the function. > * @errp can then be used without worrying about the argument being > * NULL or &error_fatal. > * > * Using it when it's not needed is safe, but please avoid cluttering > * the source with useless code. > > But in cxl_usp_realize(), @errp is dereferenced without ERRP_GUARD(): > > cxl_doe_cdat_init(cxl_cstate, errp); > if (*errp) { > goto err_cap; > } > > Here we check *errp, because cxl_doe_cdat_init() returns void. And since > cxl_usp_realize() - as a PCIDeviceClass.realize() method - doesn't get > the NULL @errp parameter, it hasn't triggered the bug that dereferencing > the NULL @errp. > > To follow the requirement of @errp, add missing ERRP_GUARD() in > cxl_usp_realize(). > > Suggested-by: Markus Armbruster <armbru@redhat.com> > Signed-off-by: Zhao Liu <zhao1.liu@intel.com> > Reviewed-by: Markus Armbruster <armbru@redhat.com> Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> > --- > Suggested by credit: > Markus: Referred his explanation about ERRP_GUARD(). > --- > v2: > * Add the @errp dereference code in commit message to make review > easier. (Markus) > --- > hw/pci-bridge/cxl_upstream.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/hw/pci-bridge/cxl_upstream.c b/hw/pci-bridge/cxl_upstream.c > index e87eb4017713..03d123cca0ef 100644 > --- a/hw/pci-bridge/cxl_upstream.c > +++ b/hw/pci-bridge/cxl_upstream.c > @@ -289,6 +289,7 @@ static void free_default_cdat_table(CDATSubHeader **cdat_table, int num, > > static void cxl_usp_realize(PCIDevice *d, Error **errp) > { > + ERRP_GUARD(); > PCIEPort *p = PCIE_PORT(d); > CXLUpstreamPort *usp = CXL_USP(d); > CXLComponentState *cxl_cstate = &usp->cxl_cstate;
On 23/02/2024 09.56, Zhao Liu wrote: > From: Zhao Liu <zhao1.liu@intel.com> > > As the comment in qapi/error, dereferencing @errp requires > ERRP_GUARD(): > > * = Why, when and how to use ERRP_GUARD() = > * > * Without ERRP_GUARD(), use of the @errp parameter is restricted: > * - It must not be dereferenced, because it may be null. > ... > * ERRP_GUARD() lifts these restrictions. > * > * To use ERRP_GUARD(), add it right at the beginning of the function. > * @errp can then be used without worrying about the argument being > * NULL or &error_fatal. > * > * Using it when it's not needed is safe, but please avoid cluttering > * the source with useless code. > > But in cxl_usp_realize(), @errp is dereferenced without ERRP_GUARD(): > > cxl_doe_cdat_init(cxl_cstate, errp); > if (*errp) { > goto err_cap; > } > > Here we check *errp, because cxl_doe_cdat_init() returns void. And since > cxl_usp_realize() - as a PCIDeviceClass.realize() method - doesn't get > the NULL @errp parameter, it hasn't triggered the bug that dereferencing > the NULL @errp. > > To follow the requirement of @errp, add missing ERRP_GUARD() in > cxl_usp_realize(). > > Suggested-by: Markus Armbruster <armbru@redhat.com> > Signed-off-by: Zhao Liu <zhao1.liu@intel.com> > Reviewed-by: Markus Armbruster <armbru@redhat.com> > --- > Suggested by credit: > Markus: Referred his explanation about ERRP_GUARD(). > --- > v2: > * Add the @errp dereference code in commit message to make review > easier. (Markus) > --- > hw/pci-bridge/cxl_upstream.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/hw/pci-bridge/cxl_upstream.c b/hw/pci-bridge/cxl_upstream.c > index e87eb4017713..03d123cca0ef 100644 > --- a/hw/pci-bridge/cxl_upstream.c > +++ b/hw/pci-bridge/cxl_upstream.c > @@ -289,6 +289,7 @@ static void free_default_cdat_table(CDATSubHeader **cdat_table, int num, > > static void cxl_usp_realize(PCIDevice *d, Error **errp) > { > + ERRP_GUARD(); > PCIEPort *p = PCIE_PORT(d); > CXLUpstreamPort *usp = CXL_USP(d); > CXLComponentState *cxl_cstate = &usp->cxl_cstate; Reviewed-by: Thomas Huth <thuth@redhat.com>
diff --git a/hw/pci-bridge/cxl_upstream.c b/hw/pci-bridge/cxl_upstream.c index e87eb4017713..03d123cca0ef 100644 --- a/hw/pci-bridge/cxl_upstream.c +++ b/hw/pci-bridge/cxl_upstream.c @@ -289,6 +289,7 @@ static void free_default_cdat_table(CDATSubHeader **cdat_table, int num, static void cxl_usp_realize(PCIDevice *d, Error **errp) { + ERRP_GUARD(); PCIEPort *p = PCIE_PORT(d); CXLUpstreamPort *usp = CXL_USP(d); CXLComponentState *cxl_cstate = &usp->cxl_cstate;