[PATCH] erofs: add unsupported inode i_format check

[Gao Xiang]

From: Gao Xiang <hsiangkao@xxxxxxxxxx>

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.

Fixes: 431339ba9042 ("staging: erofs: add inode operations")
Cc: <stable@xxxxxxxxxxxxxxx> # 4.19+
Signed-off-by: Gao Xiang <hsiangkao@xxxxxxxxxx>
---
new potential inode features can also be covered by COMPR_CFGS & BIG_PCLUSTER
in the next cycle at least, and possibly need its new sb incompat feature as
well so it's not quite vital.

 fs/erofs/erofs_fs.h | 3 +++
 fs/erofs/inode.c    | 7 +++++++
 2 files changed, 10 insertions(+)

diff --git a/fs/erofs/erofs_fs.h b/fs/erofs/erofs_fs.h
index 9ad1615f4474..e8d04d808fa6 100644
--- a/fs/erofs/erofs_fs.h
+++ b/fs/erofs/erofs_fs.h
@@ -75,6 +75,9 @@ static inline bool erofs_inode_is_data_compressed(unsigned int datamode)
 #define EROFS_I_VERSION_BIT             0
 #define EROFS_I_DATALAYOUT_BIT          1
 
+#define EROFS_I_ALL	\
+	((1 << (EROFS_I_DATALAYOUT_BIT + EROFS_I_DATALAYOUT_BITS)) - 1)
+
 /* 32-byte reduced form of an ondisk inode */
 struct erofs_inode_compact {
 	__le16 i_format;	/* inode format hints */
diff --git a/fs/erofs/inode.c b/fs/erofs/inode.c
index 119fdce1b520..7ed2d7391692 100644
--- a/fs/erofs/inode.c
+++ b/fs/erofs/inode.c
@@ -44,6 +44,13 @@ static struct page *erofs_read_inode(struct inode *inode,
 	dic = page_address(page) + *ofs;
 	ifmt = le16_to_cpu(dic->i_format);
 
+	if (ifmt & ~EROFS_I_ALL) {
+		erofs_err(inode->i_sb, "unsupported i_format %u of nid %llu",
+			  ifmt, vi->nid);
+		err = -EOPNOTSUPP;
+		goto err_out;
+	}
+
 	vi->datalayout = erofs_inode_datalayout(ifmt);
 	if (vi->datalayout >= EROFS_INODE_DATALAYOUT_MAX) {
 		erofs_err(inode->i_sb, "unsupported datalayout %u of nid %llu",
-- 
2.20.1