[PATCH 5/6] staging: erofs: detect potential multiref due to corrupted images

[Greg Kroah-Hartman]

On Mon, Aug 19, 2019 at 10:57:42PM +0800, Chao Yu wrote:
> On 2019-8-19 18:34, Gao Xiang wrote:
> > As reported by erofs-utils fuzzer, currently, multiref
> > (ondisk deduplication) hasn't been supported for now,
> > we should forbid it properly.
> > 
> > Fixes: 3883a79abd02 ("staging: erofs: introduce VLE decompression support")
> > Cc: <stable at vger.kernel.org> # 4.19+
> > Signed-off-by: Gao Xiang <gaoxiang25 at huawei.com>
> > ---
> >  drivers/staging/erofs/zdata.c | 16 ++++++++++++++--
> >  1 file changed, 14 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/staging/erofs/zdata.c b/drivers/staging/erofs/zdata.c
> > index aae2f2b8353f..5b6fef5181af 100644
> > --- a/drivers/staging/erofs/zdata.c
> > +++ b/drivers/staging/erofs/zdata.c
> > @@ -816,8 +816,16 @@ static int z_erofs_decompress_pcluster(struct super_block *sb,
> >  			pagenr = z_erofs_onlinepage_index(page);
> >  
> >  		DBG_BUGON(pagenr >= nr_pages);
> > -		DBG_BUGON(pages[pagenr]);
> >  
> > +		/*
> > +		 * currently EROFS doesn't support multiref(dedup),
> > +		 * so here erroring out one multiref page.
> > +		 */
> > +		if (unlikely(pages[pagenr])) {
> > +			DBG_BUGON(1);
> > +			SetPageError(pages[pagenr]);
> > +			z_erofs_onlinepage_endio(pages[pagenr]);
> 
> Should set err meanwhile?

I've skipped this patch in this series for now, and applied the rest.

thanks,

greg k-h