From mboxrd@z Thu Jan  1 00:00:00 1970
From: gaoxiang25@huawei.com (Gao Xiang)
Date: Mon, 19 Aug 2019 18:34:25 +0800
Subject: [PATCH 5/6] staging: erofs: detect potential multiref due to
 corrupted images
In-Reply-To: <20190819103426.87579-1-gaoxiang25@huawei.com>
References: <20190819080218.GA42231@138>
 <20190819103426.87579-1-gaoxiang25@huawei.com>
Message-ID: <20190819103426.87579-6-gaoxiang25@huawei.com>

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]);
+		}
 		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;
-- 
2.17.1