Message ID | 1434545105-5811-6-git-send-email-lersek@redhat.com |
---|---|
State | New |
Headers | show |
On Wed, Jun 17, 2015 at 02:45:03PM +0200, Laszlo Ersek wrote: > This is done mainly for improving readability, and in preparation for the > next patch, but Markus pointed out another bonus for the string being > returned: > > "No arbitrary length limit. Before the patch, it's 39 characters, and the > code breaks catastrophically when qdev_fw_name() is longer: the second > snprintf() is called with its first argument pointing beyond path[], and > its second argument underflowing to a huge size." > > Cc: Markus Armbruster <armbru@redhat.com> > Cc: Marcel Apfelbaum <marcel@redhat.com> > Cc: Michael S. Tsirkin <mst@redhat.com> > Signed-off-by: Laszlo Ersek <lersek@redhat.com> > Tested-by: Marcel Apfelbaum <marcel@redhat.com> > Reviewed-by: Marcel Apfelbaum <marcel@redhat.com> > Reviewed-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> In fact, I'd Cc stable on this one. > --- > > Notes: > v6: > - no changes > > v5: > - separate "%s@" from TARGET_FMT_plx with a space [Markus] > - copied Markus's note about "no arbitrary length limit" on the retval > into the commit message > > v4: > - unchanged > > v3: > - new in v3 > > hw/core/sysbus.c | 16 ++++++---------- > 1 file changed, 6 insertions(+), 10 deletions(-) > > diff --git a/hw/core/sysbus.c b/hw/core/sysbus.c > index b53c351..92eced9 100644 > --- a/hw/core/sysbus.c > +++ b/hw/core/sysbus.c > @@ -281,19 +281,15 @@ static void sysbus_dev_print(Monitor *mon, DeviceState *dev, int indent) > static char *sysbus_get_fw_dev_path(DeviceState *dev) > { > SysBusDevice *s = SYS_BUS_DEVICE(dev); > - char path[40]; > - int off; > - > - off = snprintf(path, sizeof(path), "%s", qdev_fw_name(dev)); > > if (s->num_mmio) { > - snprintf(path + off, sizeof(path) - off, "@"TARGET_FMT_plx, > - s->mmio[0].addr); > - } else if (s->num_pio) { > - snprintf(path + off, sizeof(path) - off, "@i%04x", s->pio[0]); > + return g_strdup_printf("%s@" TARGET_FMT_plx, qdev_fw_name(dev), > + s->mmio[0].addr); > } > - > - return g_strdup(path); > + if (s->num_pio) { > + return g_strdup_printf("%s@i%04x", qdev_fw_name(dev), s->pio[0]); > + } > + return g_strdup(qdev_fw_name(dev)); > } > > void sysbus_add_io(SysBusDevice *dev, hwaddr addr, > -- > 1.8.3.1 >
On 06/17/15 15:46, Michael S. Tsirkin wrote: > On Wed, Jun 17, 2015 at 02:45:03PM +0200, Laszlo Ersek wrote: >> This is done mainly for improving readability, and in preparation for the >> next patch, but Markus pointed out another bonus for the string being >> returned: >> >> "No arbitrary length limit. Before the patch, it's 39 characters, and the >> code breaks catastrophically when qdev_fw_name() is longer: the second >> snprintf() is called with its first argument pointing beyond path[], and >> its second argument underflowing to a huge size." >> >> Cc: Markus Armbruster <armbru@redhat.com> >> Cc: Marcel Apfelbaum <marcel@redhat.com> >> Cc: Michael S. Tsirkin <mst@redhat.com> >> Signed-off-by: Laszlo Ersek <lersek@redhat.com> >> Tested-by: Marcel Apfelbaum <marcel@redhat.com> >> Reviewed-by: Marcel Apfelbaum <marcel@redhat.com> >> Reviewed-by: Markus Armbruster <armbru@redhat.com> > > Reviewed-by: Michael S. Tsirkin <mst@redhat.com> > > In fact, I'd Cc stable on this one. Will do, thanks. Laszlo > >> --- >> >> Notes: >> v6: >> - no changes >> >> v5: >> - separate "%s@" from TARGET_FMT_plx with a space [Markus] >> - copied Markus's note about "no arbitrary length limit" on the retval >> into the commit message >> >> v4: >> - unchanged >> >> v3: >> - new in v3 >> >> hw/core/sysbus.c | 16 ++++++---------- >> 1 file changed, 6 insertions(+), 10 deletions(-) >> >> diff --git a/hw/core/sysbus.c b/hw/core/sysbus.c >> index b53c351..92eced9 100644 >> --- a/hw/core/sysbus.c >> +++ b/hw/core/sysbus.c >> @@ -281,19 +281,15 @@ static void sysbus_dev_print(Monitor *mon, DeviceState *dev, int indent) >> static char *sysbus_get_fw_dev_path(DeviceState *dev) >> { >> SysBusDevice *s = SYS_BUS_DEVICE(dev); >> - char path[40]; >> - int off; >> - >> - off = snprintf(path, sizeof(path), "%s", qdev_fw_name(dev)); >> >> if (s->num_mmio) { >> - snprintf(path + off, sizeof(path) - off, "@"TARGET_FMT_plx, >> - s->mmio[0].addr); >> - } else if (s->num_pio) { >> - snprintf(path + off, sizeof(path) - off, "@i%04x", s->pio[0]); >> + return g_strdup_printf("%s@" TARGET_FMT_plx, qdev_fw_name(dev), >> + s->mmio[0].addr); >> } >> - >> - return g_strdup(path); >> + if (s->num_pio) { >> + return g_strdup_printf("%s@i%04x", qdev_fw_name(dev), s->pio[0]); >> + } >> + return g_strdup(qdev_fw_name(dev)); >> } >> >> void sysbus_add_io(SysBusDevice *dev, hwaddr addr, >> -- >> 1.8.3.1 >>
diff --git a/hw/core/sysbus.c b/hw/core/sysbus.c index b53c351..92eced9 100644 --- a/hw/core/sysbus.c +++ b/hw/core/sysbus.c @@ -281,19 +281,15 @@ static void sysbus_dev_print(Monitor *mon, DeviceState *dev, int indent) static char *sysbus_get_fw_dev_path(DeviceState *dev) { SysBusDevice *s = SYS_BUS_DEVICE(dev); - char path[40]; - int off; - - off = snprintf(path, sizeof(path), "%s", qdev_fw_name(dev)); if (s->num_mmio) { - snprintf(path + off, sizeof(path) - off, "@"TARGET_FMT_plx, - s->mmio[0].addr); - } else if (s->num_pio) { - snprintf(path + off, sizeof(path) - off, "@i%04x", s->pio[0]); + return g_strdup_printf("%s@" TARGET_FMT_plx, qdev_fw_name(dev), + s->mmio[0].addr); } - - return g_strdup(path); + if (s->num_pio) { + return g_strdup_printf("%s@i%04x", qdev_fw_name(dev), s->pio[0]); + } + return g_strdup(qdev_fw_name(dev)); } void sysbus_add_io(SysBusDevice *dev, hwaddr addr,