On Tue, Aug 27, 2019 at 05:36:29PM +0800, Gao Xiang wrote:
> Hi Dan,
>
> Thanks for your report.
>
> On Tue, Aug 27, 2019 at 12:03:55PM +0300, Dan Carpenter wrote:
> > Hello Gao Xiang,
> >
> > This is a semi-automatic email about new static checker warnings.
> >
> > The patch 97e86a858bc3: "staging: erofs: tidy up decompression
> > frontend" from Jul 31, 2019, leads to the following Smatch complaint:
> >
> > fs/erofs/zdata.c:670 z_erofs_do_read_page()
> > error: we previously assumed 'clt->cl' could be null (see line 596)
> >
> > fs/erofs/zdata.c
> > 595 /* didn't get a valid collection previously
> > (very rare) */
> > 596 if (!clt->cl)
> > ^^^^^^^^
> > New NULL check.
> >
> > 597 goto restart_now;
> > 598 goto hitted;
> > 599 }
> > 600
> > 601 /* go ahead the next map_blocks */
> > 602 debugln("%s: [out-of-range] pos %llu", __func__, offset
> > + cur);
> > 603
> > 604 if (z_erofs_collector_end(clt))
> > 605 fe->backmost = false;
> > 606
> > 607 map->m_la = offset + cur;
> > 608 map->m_llen = 0;
> > 609 err = z_erofs_map_blocks_iter(inode, map, 0);
> > 610 if (unlikely(err))
> > 611 goto err_out;
> > 612
> > 613 restart_now:
> > 614 if (unlikely(!(map->m_flags & EROFS_MAP_MAPPED)))
> > 615 goto hitted;
> > 616
> > 617 err = z_erofs_collector_begin(clt, inode, map);
>
> At a glance, clt->cl will be all initialized in all successful paths
> in z_erofs_collector_begin, or it all fall back into err_out...
> I have no idea what is wrong here...
>
> Some detailed path from Smatch for NIL dereferences?
>
Ah. Sorry for that. It's a false positive. I will investigate and
fix Smatch.
regards,
dan carpenter
