[PATCH for-4.19 2/4] staging: erofs: some compressed cluster should be submitted for corrupted images

[Gao Xiang]

commit ee45197c807895e156b2be0abcaebdfc116487c8 upstream.

As reported by erofs_utils fuzzer, a logical page can belong
to at most 2 compressed clusters, if one compressed cluster
is corrupted, but the other has been ready in submitting chain.

The chain needs to submit anyway in order to keep the page
working properly (page unlocked with PG_error set, PG_uptodate
not set).

Let's fix it now.

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>
Reviewed-by: Chao Yu <yuchao0 at huawei.com>
Link: https://lore.kernel.org/r/20190819103426.87579-2-gaoxiang25@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
[ Gao Xiang: Manually backport to v4.19.y stable. ]
Signed-off-by: Gao Xiang <gaoxiang25 at huawei.com>
---
 drivers/staging/erofs/unzip_vle.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/staging/erofs/unzip_vle.c b/drivers/staging/erofs/unzip_vle.c
index ad6fe6d9d00a..fc44f5ce670b 100644
--- a/drivers/staging/erofs/unzip_vle.c
+++ b/drivers/staging/erofs/unzip_vle.c
@@ -1335,19 +1335,18 @@ static int z_erofs_vle_normalaccess_readpage(struct file *file,
 	err = z_erofs_do_read_page(&f, page, &pagepool);
 	(void)z_erofs_vle_work_iter_end(&f.builder);
 
-	if (err) {
+	/* if some compressed cluster ready, need submit them anyway */
+	z_erofs_submit_and_unzip(&f, &pagepool, true);
+
+	if (err)
 		errln("%s, failed to read, err [%d]", __func__, err);
-		goto out;
-	}
 
-	z_erofs_submit_and_unzip(&f, &pagepool, true);
-out:
 	if (f.m_iter.mpage != NULL)
 		put_page(f.m_iter.mpage);
 
 	/* clean up the remaining free pages */
 	put_pages_list(&pagepool);
-	return 0;
+	return err;
 }
 
 static inline int __z_erofs_vle_normalaccess_readpages(
-- 
2.17.1