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

2019-08-19 10:36:41

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

2019-08-19 14:58:57

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

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: <[email protected]> # 4.19+
> Signed-off-by: Gao Xiang <[email protected]>
> ---
> 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?

> + }
> pages[pagenr] = page;
> }
> z_erofs_pagevec_ctor_exit(&ctor, true);
> @@ -849,7 +857,11 @@ 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]);
> + if (unlikely(pages[pagenr])) {
> + DBG_BUGON(1);
> + SetPageError(pages[pagenr]);
> + z_erofs_onlinepage_endio(pages[pagenr]);
> + }
> pages[pagenr] = page;
>
> overlapped = true;
>

2019-08-21 02:25:52

by Greg Kroah-Hartman

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

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: <[email protected]> # 4.19+
> > Signed-off-by: Gao Xiang <[email protected]>
> > ---
> > 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

2019-08-21 14:04:50

by Gao Xiang

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Subject: [PATCH v2 5/6] staging: erofs: detect potential multiref due to corrupted images

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: <[email protected]> # 4.19+
Signed-off-by: Gao Xiang <[email protected]>
---

changelog from v1:
- change err = -EFSCORRUPTED as well as Chao suggested;
[ the difference between adding err or not to [PATCH 5/6] is just whether
we error out the whole compressed cluster or partial of them (since some
pages could be decompressed successfully), it's an undefined behavior
for these corrupted compressed images... ]

Hi Chao,
Could you kindly review it again? Thanks!

Hi Greg,
This is [PATCH 5/6] of the original patchset, and I fix as what Chao suggested...
But I'm not sure whether it should be merged right now, it is up to you. :)

Thanks,
Gao Xiang

drivers/staging/erofs/zdata.c | 20 +++++++++++++++++---
1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/erofs/zdata.c b/drivers/staging/erofs/zdata.c
index 4d6faaab04f5..60d7c20db87d 100644
--- a/drivers/staging/erofs/zdata.c
+++ b/drivers/staging/erofs/zdata.c
@@ -798,6 +798,7 @@ static int z_erofs_decompress_pcluster(struct super_block *sb,
for (i = 0; i < nr_pages; ++i)
pages[i] = NULL;

+ err = 0;
z_erofs_pagevec_ctor_init(&ctor, Z_EROFS_NR_INLINE_PAGEVECS,
cl->pagevec, 0);

@@ -819,8 +820,17 @@ 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]);
+ err = -EFSCORRUPTED;
+ }
pages[pagenr] = page;
}
z_erofs_pagevec_ctor_exit(&ctor, true);
@@ -828,7 +838,6 @@ static int z_erofs_decompress_pcluster(struct super_block *sb,
overlapped = false;
compressed_pages = pcl->compressed_pages;

- err = 0;
for (i = 0; i < clusterpages; ++i) {
unsigned int pagenr;

@@ -852,7 +861,12 @@ 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]);
+ if (unlikely(pages[pagenr])) {
+ DBG_BUGON(1);
+ SetPageError(pages[pagenr]);
+ z_erofs_onlinepage_endio(pages[pagenr]);
+ err = -EFSCORRUPTED;
+ }
pages[pagenr] = page;

overlapped = true;
--
2.17.1

2019-08-21 14:25:37

by Chao Yu

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Subject: Re: [PATCH v2 5/6] staging: erofs: detect potential multiref due to corrupted images

On 2019-8-21 22:01, 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: <[email protected]> # 4.19+
> Signed-off-by: Gao Xiang <[email protected]>

Reviewed-by: Chao Yu <[email protected]>

Thanks,