Re: Oops when using growisofs

Nick Piggin
2008-06-23T07:00:09Z

On Monday 23 June 2008 16:34, Andrew Morton wrote:
> On Mon, 23 Jun 2008 00:28:20 +0200 Michael Buesch <mb@bu3sch.de> wrote:
> > On Monday 23 June 2008 00:05:51 Michael Buesch wrote:
> > > > Note: r9 and r3 are both NULL pointers. r3 is the value returned from
> > > > alloc_page_buffers. R9 is a copy of that, which gets accessed.
> > >
> > > Hm, yeah. I looked at that code already, but I can't see how it could
> > > return a NULL pointer.
> >
> > Well, actually, it can return a NULL pointer.
> >
> > 928 head = NULL;
> > 929 offset = PAGE_SIZE;
> > 930 while ((offset -= size) >= 0) {
> > ...
> > 949 }
> > 950 return head;
> >
> > So if size, which is a passed in as parameter, is > PAGE_SIZE it will
> > return NULL.
> >
> > The size parameter is calculated by doing
> > blocksize = 1 << inode->i_blkbits;
> > in an earlier function in the callchain.
>
> Yes, that's a more likely scenario. isofs has a history of passing
> garbage into the VFS.

Yes isofs will pass in a too-big page here (IIRC 32K or something).
And trigger this oops.