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Re: [Qemu-devel] [PATCH] qdev-monitor: fix segmentation fault on qdev_de
From: |
Gonglei (Arei) |
Subject: |
Re: [Qemu-devel] [PATCH] qdev-monitor: fix segmentation fault on qdev_device_help() |
Date: |
Tue, 16 Sep 2014 07:38:07 +0000 |
> From: Markus Armbruster [mailto:address@hidden
> Sent: Tuesday, September 16, 2014 3:28 PM
> Subject: Re: [Qemu-devel] [PATCH] qdev-monitor: fix segmentation fault on
> qdev_device_help()
>
> <address@hidden> writes:
>
> > From: Gonglei <address@hidden>
> >
> > Normally, qmp_device_list_properties() may return NULL when
> > a device haven't special properties excpet Object and DeviceState
> > properties, such as virtio-balloon-device.
> >
> > We just need check local_err instead of prop_list.
> >
> > Example:
> >
> > Segmentation fault (core dumped)
> >
> > The backtrace as below:
> >
> > Program received signal SIGSEGV, Segmentation fault.
> > 0x00005555559af1a8 in error_get_pretty (err=0x0) at util/error.c:152
> > 152 return err->msg;
> > (gdb) bt
> > #0 0x00005555559af1a8 in error_get_pretty (err=0x0) at util/error.c:152
> > #1 0x000055555572fce9 in qdev_device_help (opts=0x5555562fdfe0) at
> qdev-monitor.c:210
> > #2 0x000055555574a6f2 in device_help_func (opts=0x5555562fdfe0,
> opaque=0x0) at vl.c:2362
> > #3 0x00005555559c0a33 in qemu_opts_foreach (list=0x555555dd0b40
> <qemu_device_opts>,
> > func=0x55555574a6ca <device_help_func>, opaque=0x0,
> abort_on_failure=0) at util/qemu-option.c:1072
> > #4 0x000055555574f514 in main (argc=3, argv=0x7fffffffe218,
> envp=0x7fffffffe238) at vl.c:4246
> >
> > Signed-off-by: Gonglei <address@hidden>
> > ---
> > qdev-monitor.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/qdev-monitor.c b/qdev-monitor.c
> > index fb9ee24..5ec6606 100644
> > --- a/qdev-monitor.c
> > +++ b/qdev-monitor.c
> > @@ -206,7 +206,7 @@ int qdev_device_help(QemuOpts *opts)
> > }
> >
> > prop_list = qmp_device_list_properties(driver, &local_err);
> > - if (!prop_list) {
> > + if (local_err) {
> > error_printf("%s\n", error_get_pretty(local_err));
> > error_free(local_err);
> > return 1;
>
> Doesn't this leak prop_list when local_err && prop_list?
>
No, it will not happen this situation.
> Returning both a value in need of destruction and an error object is at
> least highly unusual, and probably plain wrong.
>
> Should qmp_device_list_properties() return NULL when it sets an error?
Yes, it was.
Best regards,
-Gonglei