On Tue, 2012-07-10 at 18:04 +0200, Jan Kara wrote:
> On Tue 10-07-12 16:52:26, Ben Hutchings wrote:
> > On Mon, Jul 09, 2012 at 03:31:42PM +0100, Ben Hutchings wrote:
> > > 3.2-stable review patch. If anyone has any objections, please let me
> > > know.
> > >
> > > ------------------
> > >
> > > From: Jan Kara <j...@suse.cz>
> > >
> > > commit adee11b2085bee90bd8f4f52123ffb07882d6256 upstream.
> > >
> > > Check provided length of partition table so that (possibly maliciously)
> > > corrupted partition table cannot cause accessing data beyond current
> > > buffer.
> > >
> > > Signed-off-by: Jan Kara <j...@suse.cz>
> > > Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
> > > ---
> > > fs/udf/super.c | 10 +++++++++-
> > > 1 file changed, 9 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/fs/udf/super.c b/fs/udf/super.c
> > > index 9da6f4e..ce911f5 100644
> > > --- a/fs/udf/super.c
> > > +++ b/fs/udf/super.c
> > [...]
> > > @@ -1232,13 +1233,20 @@ static int udf_load_logicalvol(struct super_block
> > > *sb, sector_t block,
> > > return 1;
> > > BUG_ON(ident != TAG_IDENT_LVD);
> > > lvd = (struct logicalVolDesc *)bh->b_data;
> > > + table_len = le32_to_cpu(lvd->mapTableLength);
> > > + if (sizeof(*lvd) + table_len > sb->s_blocksize) {
> > [...]
> >
> > I don't think this is sufficient, unless there has been some prior
> > validation of lvd->mapTableLength. On a 32-bit machine, the addition
> > may overflow. The untrusted value has to be validated before doing
> > any arithmetic on it, e.g.:
> >
> > if (table_len > sb->s_blocksize - sizeof(*lv)) {
> Yeah, thanks for spotting this! I've queued the attached patch. I don't
> find this really pressing so I'll push it in the next merge window. OK?
It's the sort of thing that I would expect to go into distribution
security updates a.s.a.p. I don't see why it should wait that long
(though of course the merge window isn't *that* far away).
Ben.
--
Ben Hutchings
The generation of random numbers is too important to be left to chance.
- Robert Coveyou
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