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Subject[PATCH 4.19 111/114] staging: erofs: detect potential multiref due to corrupted images
Date
From: Gao Xiang <gaoxiang25@huawei.com>

commit e12a0ce2fa69798194f3a8628baf6edfbd5c548f upstream.

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@vger.kernel.org> # 4.19+
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Link: https://lore.kernel.org/r/20190821140152.229648-1-gaoxiang25@huawei.com
[ Gao Xiang: Since earlier kernels don't define EFSCORRUPTED,
let's use EIO instead. ]
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/staging/erofs/unzip_vle.c | 20 +++++++++++++++++---
1 file changed, 17 insertions(+), 3 deletions(-)

--- a/drivers/staging/erofs/unzip_vle.c
+++ b/drivers/staging/erofs/unzip_vle.c
@@ -857,6 +857,7 @@ repeat:
for (i = 0; i < nr_pages; ++i)
pages[i] = NULL;

+ err = 0;
z_erofs_pagevec_ctor_init(&ctor,
Z_EROFS_VLE_INLINE_PAGEVECS, work->pagevec, 0);

@@ -878,8 +879,17 @@ repeat:
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 (pages[pagenr]) {
+ DBG_BUGON(1);
+ SetPageError(pages[pagenr]);
+ z_erofs_onlinepage_endio(pages[pagenr]);
+ err = -EIO;
+ }
pages[pagenr] = page;
}
sparsemem_pages = i;
@@ -889,7 +899,6 @@ repeat:
overlapped = false;
compressed_pages = grp->compressed_pages;

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

@@ -915,7 +924,12 @@ repeat:
pagenr = z_erofs_onlinepage_index(page);

DBG_BUGON(pagenr >= nr_pages);
- DBG_BUGON(pages[pagenr]);
+ if (pages[pagenr]) {
+ DBG_BUGON(1);
+ SetPageError(pages[pagenr]);
+ z_erofs_onlinepage_endio(pages[pagenr]);
+ err = -EIO;
+ }
++sparsemem_pages;
pages[pagenr] = page;


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