[PATCH 4.19 018/425] erofs: add unsupported inode i_format check

[Greg Kroah-Hartman]

From: Gao Xiang <hsiangkao@xxxxxxxxxx>

commit 24a806d849c0b0c1d0cd6a6b93ba4ae4c0ec9f08 upstream.

If any unknown i_format fields are set (may be of some new incompat
inode features), mark such inode as unsupported.

Just in case of any new incompat i_format fields added in the future.

Link: https://lore.kernel.org/r/20210329003614.6583-1-hsiangkao@xxxxxxx
Fixes: 431339ba9042 ("staging: erofs: add inode operations")
Cc: <stable@xxxxxxxxxxxxxxx> # 4.19+
Signed-off-by: Gao Xiang <hsiangkao@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/staging/erofs/erofs_fs.h |    3 +++
 drivers/staging/erofs/inode.c    |    6 ++++++
 2 files changed, 9 insertions(+)

--- a/drivers/staging/erofs/erofs_fs.h
+++ b/drivers/staging/erofs/erofs_fs.h
@@ -71,6 +71,9 @@ enum {
 #define EROFS_I_VERSION_BIT             0
 __EROFS_BIT(EROFS_I_, DATA_MAPPING, VERSION);
 
+#define EROFS_I_ALL	\
+	((1 << (EROFS_I_DATA_MAPPING_BIT + EROFS_I_DATA_MAPPING_BITS)) - 1)
+
 struct erofs_inode_v1 {
 /*  0 */__le16 i_advise;
 
--- a/drivers/staging/erofs/inode.c
+++ b/drivers/staging/erofs/inode.c
@@ -48,6 +48,12 @@ static struct page *read_inode(struct in
 	v1 = page_address(page) + *ofs;
 	ifmt = le16_to_cpu(v1->i_advise);
 
+	if (ifmt & ~EROFS_I_ALL) {
+		errln("unsupported i_format %u of nid %llu", ifmt, vi->nid);
+		err = -EOPNOTSUPP;
+		goto err_out;
+	}
+
 	vi->data_mapping_mode = __inode_data_mapping(ifmt);
 	if (unlikely(vi->data_mapping_mode >= EROFS_INODE_LAYOUT_MAX)) {
 		errln("unknown data mapping mode %u of nid %llu",