Messages in this thread | | | Date | Mon, 4 Jan 2021 15:27:50 -0500 | From | Mike Snitzer <> | Subject | Re: dm snap : add sanity checks to snapshot_ctr |
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On Fri, Dec 25 2020 at 1:48am -0500, Defang Bo <bodefang@126.com> wrote:
> Similar to commit<70de2cbd>,there should be a check for argc and argv to prevent Null pointer dereferencing > when the dm_get_device invoked twice on the same device path with differnt mode. > > Signed-off-by: Defang Bo <bodefang@126.com> > --- > drivers/md/dm-snap.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c > index 4668b2c..dccce8b 100644 > --- a/drivers/md/dm-snap.c > +++ b/drivers/md/dm-snap.c > @@ -1258,6 +1258,13 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv) > > as.argc = argc; > as.argv = argv; > + > + if (!strcmp(argv[0], argv[1])) { > + ti->error = "Error setting metadata or data device"; > + r = -EINVAL; > + goto bad; > + } > + > dm_consume_args(&as, 4); > r = parse_snapshot_features(&as, s, ti); > if (r) > -- > 2.7.4 >
We already have this later in snapshot_ctr:
if (cow_dev && cow_dev == origin_dev) { ti->error = "COW device cannot be the same as origin device"; r = -EINVAL; goto bad_cow; }
Which happens before the 2nd dm_get_device() for the cow device. So I'm not seeing how you could experience the NULL pointer you say is possible.
Mike
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