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: <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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/staging/erofs/zdata.c b/drivers/staging/erofs/zdata.c
index 4d6faaa..60d7c20 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;
