| Message ID | 1400606439-19899-1-git-send-email-mdroth@linux.vnet.ibm.com |
|---|---|
| State | New |
| Headers | show |
Michael Roth <mdroth@linux.vnet.ibm.com> writes: > In general QMP command parameter values are specified by consumers of the > QMP/HMP interface, but in the case of optional parameters these values may > be left uninitialized. > > It is considered a bug for code to make use of optional parameters that have > not been flagged as being present by the marshalling code (via corresponding > has_<parameter> parameter), however our marshalling code will still pass > these uninitialized values on to the corresponding QMP function (to then > be ignored). Some compilers (clang in particular) consider this unsafe > however, and generate warnings as a result. As reported by Peter Maydell: > > This is something clang's -fsanitize=undefined spotted. The > code generated by qapi-commands.py in qmp-marshal.c for > qmp_marshal_* functions where there are some optional > arguments looks like this: > > bool has_force = false; > bool force; > > mi = qmp_input_visitor_new_strict(QOBJECT(args)); > v = qmp_input_get_visitor(mi); > visit_type_str(v, &device, "device", errp); > visit_start_optional(v, &has_force, "force", errp); > if (has_force) { > visit_type_bool(v, &force, "force", errp); > } > visit_end_optional(v, errp); > qmp_input_visitor_cleanup(mi); > > if (error_is_set(errp)) { > goto out; > } > qmp_eject(device, has_force, force, errp); > > In the case where has_force is false, we never initialize > force, but then we use it by passing it to qmp_eject. > I imagine we don't then actually use the value, but clang > complains in particular for 'bool' variables because the value > that ends up being loaded from memory for 'force' is not either > 0 or 1 (being uninitialized stack contents). > > Fix this by initializing all QMP command parameters to {0} in the > marshalling code prior to passing them on to the QMP functions. > > Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com> > Reported-by: Peter Maydell <peter.maydell@linaro.org> > Tested-by: Peter Maydell <peter.maydell@linaro.org> > Reviewed-by: Eric Blake <eblake@redhat.com> > --- > scripts/qapi-commands.py | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/scripts/qapi-commands.py b/scripts/qapi-commands.py > index 386f17e..7d93d01 100644 > --- a/scripts/qapi-commands.py > +++ b/scripts/qapi-commands.py > @@ -111,7 +111,7 @@ bool has_%(argname)s = false; > argname=c_var(argname), argtype=c_type(argtype)) > else: > ret += mcgen(''' > -%(argtype)s %(argname)s; > +%(argtype)s %(argname)s = {0}; > ''', > argname=c_var(argname), argtype=c_type(argtype)) Thanks for the clear commit message. Reviewed-by: Markus Armbruster <armbru@redhat.com>
On 20 May 2014 18:20, Michael Roth <mdroth@linux.vnet.ibm.com> wrote: > In general QMP command parameter values are specified by consumers of the > QMP/HMP interface, but in the case of optional parameters these values may > be left uninitialized. > > It is considered a bug for code to make use of optional parameters that have > not been flagged as being present by the marshalling code (via corresponding > has_<parameter> parameter), however our marshalling code will still pass > these uninitialized values on to the corresponding QMP function (to then > be ignored). Some compilers (clang in particular) consider this unsafe > however, and generate warnings as a result. As reported by Peter Maydell: > > This is something clang's -fsanitize=undefined spotted. The > code generated by qapi-commands.py in qmp-marshal.c for > qmp_marshal_* functions where there are some optional > arguments looks like this: > > bool has_force = false; > bool force; > > mi = qmp_input_visitor_new_strict(QOBJECT(args)); > v = qmp_input_get_visitor(mi); > visit_type_str(v, &device, "device", errp); > visit_start_optional(v, &has_force, "force", errp); > if (has_force) { > visit_type_bool(v, &force, "force", errp); > } > visit_end_optional(v, errp); > qmp_input_visitor_cleanup(mi); > > if (error_is_set(errp)) { > goto out; > } > qmp_eject(device, has_force, force, errp); > > In the case where has_force is false, we never initialize > force, but then we use it by passing it to qmp_eject. > I imagine we don't then actually use the value, but clang > complains in particular for 'bool' variables because the value > that ends up being loaded from memory for 'force' is not either > 0 or 1 (being uninitialized stack contents). > > Fix this by initializing all QMP command parameters to {0} in the > marshalling code prior to passing them on to the QMP functions. > > Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com> > Reported-by: Peter Maydell <peter.maydell@linaro.org> > Tested-by: Peter Maydell <peter.maydell@linaro.org> > Reviewed-by: Eric Blake <eblake@redhat.com> Had I tested this before? In any case I have now :-) It fixes the more recent clang compile warning as well as the more long standing sanitizer runtime complaints. thanks -- PMM
Quoting Peter Maydell (2014-05-20 13:21:15) > On 20 May 2014 18:20, Michael Roth <mdroth@linux.vnet.ibm.com> wrote: > > In general QMP command parameter values are specified by consumers of the > > QMP/HMP interface, but in the case of optional parameters these values may > > be left uninitialized. > > > > It is considered a bug for code to make use of optional parameters that have > > not been flagged as being present by the marshalling code (via corresponding > > has_<parameter> parameter), however our marshalling code will still pass > > these uninitialized values on to the corresponding QMP function (to then > > be ignored). Some compilers (clang in particular) consider this unsafe > > however, and generate warnings as a result. As reported by Peter Maydell: > > > > This is something clang's -fsanitize=undefined spotted. The > > code generated by qapi-commands.py in qmp-marshal.c for > > qmp_marshal_* functions where there are some optional > > arguments looks like this: > > > > bool has_force = false; > > bool force; > > > > mi = qmp_input_visitor_new_strict(QOBJECT(args)); > > v = qmp_input_get_visitor(mi); > > visit_type_str(v, &device, "device", errp); > > visit_start_optional(v, &has_force, "force", errp); > > if (has_force) { > > visit_type_bool(v, &force, "force", errp); > > } > > visit_end_optional(v, errp); > > qmp_input_visitor_cleanup(mi); > > > > if (error_is_set(errp)) { > > goto out; > > } > > qmp_eject(device, has_force, force, errp); > > > > In the case where has_force is false, we never initialize > > force, but then we use it by passing it to qmp_eject. > > I imagine we don't then actually use the value, but clang > > complains in particular for 'bool' variables because the value > > that ends up being loaded from memory for 'force' is not either > > 0 or 1 (being uninitialized stack contents). > > > > Fix this by initializing all QMP command parameters to {0} in the > > marshalling code prior to passing them on to the QMP functions. > > > > Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com> > > Reported-by: Peter Maydell <peter.maydell@linaro.org> > > Tested-by: Peter Maydell <peter.maydell@linaro.org> > > Reviewed-by: Eric Blake <eblake@redhat.com> > > Had I tested this before? In any case I have now :-) > > It fixes the more recent clang compile warning as well as > the more long standing sanitizer runtime complaints. Thanks! You added your Tested-by: in the original thread, but it was probably old enough to warrant another test run :) > > thanks > -- PMM
On Tue, 20 May 2014 12:20:39 -0500 Michael Roth <mdroth@linux.vnet.ibm.com> wrote: > In general QMP command parameter values are specified by consumers of the > QMP/HMP interface, but in the case of optional parameters these values may > be left uninitialized. > > It is considered a bug for code to make use of optional parameters that have > not been flagged as being present by the marshalling code (via corresponding > has_<parameter> parameter), however our marshalling code will still pass > these uninitialized values on to the corresponding QMP function (to then > be ignored). Some compilers (clang in particular) consider this unsafe > however, and generate warnings as a result. As reported by Peter Maydell: > > This is something clang's -fsanitize=undefined spotted. The > code generated by qapi-commands.py in qmp-marshal.c for > qmp_marshal_* functions where there are some optional > arguments looks like this: > > bool has_force = false; > bool force; > > mi = qmp_input_visitor_new_strict(QOBJECT(args)); > v = qmp_input_get_visitor(mi); > visit_type_str(v, &device, "device", errp); > visit_start_optional(v, &has_force, "force", errp); > if (has_force) { > visit_type_bool(v, &force, "force", errp); > } > visit_end_optional(v, errp); > qmp_input_visitor_cleanup(mi); > > if (error_is_set(errp)) { > goto out; > } > qmp_eject(device, has_force, force, errp); > > In the case where has_force is false, we never initialize > force, but then we use it by passing it to qmp_eject. > I imagine we don't then actually use the value, but clang > complains in particular for 'bool' variables because the value > that ends up being loaded from memory for 'force' is not either > 0 or 1 (being uninitialized stack contents). > > Fix this by initializing all QMP command parameters to {0} in the > marshalling code prior to passing them on to the QMP functions. > > Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com> > Reported-by: Peter Maydell <peter.maydell@linaro.org> > Tested-by: Peter Maydell <peter.maydell@linaro.org> > Reviewed-by: Eric Blake <eblake@redhat.com> > --- > scripts/qapi-commands.py | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) Applied to the qmp branch, thanks. > > diff --git a/scripts/qapi-commands.py b/scripts/qapi-commands.py > index 386f17e..7d93d01 100644 > --- a/scripts/qapi-commands.py > +++ b/scripts/qapi-commands.py > @@ -111,7 +111,7 @@ bool has_%(argname)s = false; > argname=c_var(argname), argtype=c_type(argtype)) > else: > ret += mcgen(''' > -%(argtype)s %(argname)s; > +%(argtype)s %(argname)s = {0}; > ''', > argname=c_var(argname), argtype=c_type(argtype)) >
diff --git a/scripts/qapi-commands.py b/scripts/qapi-commands.py index 386f17e..7d93d01 100644 --- a/scripts/qapi-commands.py +++ b/scripts/qapi-commands.py @@ -111,7 +111,7 @@ bool has_%(argname)s = false; argname=c_var(argname), argtype=c_type(argtype)) else: ret += mcgen(''' -%(argtype)s %(argname)s; +%(argtype)s %(argname)s = {0}; ''', argname=c_var(argname), argtype=c_type(argtype))
In general QMP command parameter values are specified by consumers of the QMP/HMP interface, but in the case of optional parameters these values may be left uninitialized. It is considered a bug for code to make use of optional parameters that have not been flagged as being present by the marshalling code (via corresponding has_<parameter> parameter), however our marshalling code will still pass these uninitialized values on to the corresponding QMP function (to then be ignored). Some compilers (clang in particular) consider this unsafe however, and generate warnings as a result. As reported by Peter Maydell: This is something clang's -fsanitize=undefined spotted. The code generated by qapi-commands.py in qmp-marshal.c for qmp_marshal_* functions where there are some optional arguments looks like this: bool has_force = false; bool force; mi = qmp_input_visitor_new_strict(QOBJECT(args)); v = qmp_input_get_visitor(mi); visit_type_str(v, &device, "device", errp); visit_start_optional(v, &has_force, "force", errp); if (has_force) { visit_type_bool(v, &force, "force", errp); } visit_end_optional(v, errp); qmp_input_visitor_cleanup(mi); if (error_is_set(errp)) { goto out; } qmp_eject(device, has_force, force, errp); In the case where has_force is false, we never initialize force, but then we use it by passing it to qmp_eject. I imagine we don't then actually use the value, but clang complains in particular for 'bool' variables because the value that ends up being loaded from memory for 'force' is not either 0 or 1 (being uninitialized stack contents). Fix this by initializing all QMP command parameters to {0} in the marshalling code prior to passing them on to the QMP functions. Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com> Reported-by: Peter Maydell <peter.maydell@linaro.org> Tested-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Eric Blake <eblake@redhat.com> --- scripts/qapi-commands.py | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)