Re: [PATCH v2] Check and report for incomplete 'global' option format

[Rohit Kumar]

On 15/02/22 3:00 pm, Markus Armbruster wrote:
> Rohit Kumar <rohit.kumar3@nutanix.com> writes:
>
> > Qemu might crash when provided incomplete '-global' option.
> > For example:
> >          qemu-system-x86_64 -global driver=isa-fdc
> >          qemu-system-x86_64: ../../devel/qemu/qapi/string-input-visitor.c:394:
> >          string_input_visitor_new: Assertion `str' failed.
> >          Aborted (core dumped)
> >
> > Resolves: 
> > https://urldefense.proofpoint.com/v2/url?u=https-3A__gitlab.com_qemu-2Dproject_qemu_-2D_issues_604&d=DwIBAg&c=s883GpUCOChKOHiocYtGcg&r=ABSkr7gy7ZTfApFfI-Xxt1gZNtsDDiXoXOXc0OrkyFs&m=YfuOt9ozXVjjleGOXTdWK4Hu8PoU3kTzGTXAJ223138_AM934NRnuqUQHpaLSWTs&s=WEGcm58m7pR4XrWGsUvHOVPj18ym0OrlAObwY_CfKlc&e=
> The original qemu_global_option() only ever created QemuOpts with all
> three options present.  Code consuming these QemuOpts relies on this
> invariant.  Commit 3751d7c43f "vl: allow full-blown QemuOpts syntax for
> -global" (v2.4.0) wrecked it.
>
> Let's point to the root cause:
>
>    Fixes: 3751d7c43f795b45ffdb9429cfb09c6beea55c68
Thanks, Markus for pointing out this. I will add it in the next patch.
> > Signed-off-by: Rohit Kumar <rohit.kumar3@nutanix.com>
> > ---
> >   diff to v1:
> >    - Removed '\n' from error log message.
> >
> >   softmmu/qdev-monitor.c | 8 +++++++-
> >   1 file changed, 7 insertions(+), 1 deletion(-)
> >
> > diff --git a/softmmu/qdev-monitor.c b/softmmu/qdev-monitor.c
> > index 01f3834db5..51b33caeca 100644
> > --- a/softmmu/qdev-monitor.c
> > +++ b/softmmu/qdev-monitor.c
> > @@ -1020,6 +1020,7 @@ int qemu_global_option(const char *str)
> >       char driver[64], property[64];
> >       QemuOpts *opts;
> >       int rc, offset;
> > +    Error *err = NULL;
> >   
> >       rc = sscanf(str, "%63[^.=].%63[^=]%n", driver, property, &offset);
> >       if (rc == 2 && str[offset] == '=') {
> > @@ -1031,7 +1032,12 @@ int qemu_global_option(const char *str)
> >       }
> >   
> >       opts = qemu_opts_parse_noisily(&qemu_global_opts, str, false);
> > -    if (!opts) {
> > +    if (!opts || !qemu_opt_get(opts, "driver") || 
> > !qemu_opt_get(opts,"property") ||
> > +    !qemu_opt_get(opts, "value")) {
> > +        error_setg(&err, "Invalid 'global' option format! "
> > +        "Use -global <driver>.<property>=<value> or "
> > +        "-global driver=driver,property=property,value=value");
> > +        error_report_err(err);
> >           return -1;
> >       }
> This fix isn't quite right.
>
> When qemu_opts_parse_noisily() fails, it reports an error and returns
> null.  Your patch reports a second error then.  Reproducer:
>
>      $ qemu-system-x86_64 -global =
>      qemu-system-x86_64: -global =: Invalid parameter ''
>      qemu-system-x86_64: -global =: Invalid 'global' option format! Use -global 
> <driver>.<property>=<value> or -global 
> driver=driver,property=property,value=value
>
> You should do something like
>
>      opts = qemu_opts_parse_noisily(&qemu_global_opts, str, false);
>      if (!opts) {
>          return -1;
>      }
>      if (!qemu_opt_get(opts, "driver")
>          || !qemu_opt_get(opts, "property")
>          || !qemu_opt_get(opts, "value")) {
>          error_report("options 'driver', 'property', and 'value'"
>                       " are required');
>          return -1;
>      }
Ack., I will update it in the next patch. Thanks.