[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] xen/blkback: prevent leak of mode during multiple backend_changed calls
>>> On 05.12.12 at 11:01, Olaf Hering <olaf@xxxxxxxxx> wrote: > backend_changed might be called multiple times, which will leak > be->mode. free the previous value before storing the current mode value. As said before - this is one possible route to take. But did you consider at all the alternative of preventing the function from getting called more than once for a given device? As also said before, I think that would have other bad effects, and hence should be preferred (and would likely also result in a smaller patch). And _if_ this here is the route to go, I'd clearly see this and your earlier patch to be folded into just one (dealing with both leaks in one go). Jan > Signed-off-by: Olaf Hering <olaf@xxxxxxxxx> > --- > > !! Not compile tested !! > > drivers/block/xen-blkback/xenbus.c | 12 +++++++----- > 1 file changed, 7 insertions(+), 5 deletions(-) > > diff --git a/drivers/block/xen-blkback/xenbus.c > b/drivers/block/xen-blkback/xenbus.c > index a6585a4..8650b19 100644 > --- a/drivers/block/xen-blkback/xenbus.c > +++ b/drivers/block/xen-blkback/xenbus.c > @@ -502,7 +502,7 @@ static void backend_changed(struct xenbus_watch *watch, > = container_of(watch, struct backend_info, backend_watch); > struct xenbus_device *dev = be->dev; > int cdrom = 0; > - char *device_type; > + char *mode, *device_type; > > DPRINTK(""); > > @@ -528,13 +528,15 @@ static void backend_changed(struct xenbus_watch *watch, > return; > } > > - be->mode = xenbus_read(XBT_NIL, dev->nodename, "mode", NULL); > - if (IS_ERR(be->mode)) { > - err = PTR_ERR(be->mode); > + mode = xenbus_read(XBT_NIL, dev->nodename, "mode", NULL); > + kfree(be->mode); > + if (IS_ERR(mode)) { > + err = PTR_ERR(mode); > be->mode = NULL; > xenbus_dev_fatal(dev, err, "reading mode"); > return; > } > + be->mode = mode; > > device_type = xenbus_read(XBT_NIL, dev->otherend, "device-type", NULL); > if (!IS_ERR(device_type)) { > @@ -555,7 +557,7 @@ static void backend_changed(struct xenbus_watch *watch, > be->minor = minor; > > err = xen_vbd_create(be->blkif, handle, major, minor, > - (NULL == strchr(be->mode, 'w')), cdrom); > + (NULL == strchr(mode, 'w')), cdrom); > if (err) { > be->major = 0; > be->minor = 0; > -- > 1.8.0.1 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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