[PATCH] erofs-utils: lib: restrict pcluster size limitations

[Gao Xiang]

Source kernel commit: 7c3ca1838a7831855cbf2e6927a10e0e4723edf6
Signed-off-by: Gao Xiang <hsiangkao at linux.alibaba.com>
---
 include/erofs_fs.h |  5 ++++-
 lib/zmap.c         | 41 ++++++++++++++++++++---------------------
 2 files changed, 24 insertions(+), 22 deletions(-)

diff --git a/include/erofs_fs.h b/include/erofs_fs.h
index 5672c99..269d302 100644
--- a/include/erofs_fs.h
+++ b/include/erofs_fs.h
@@ -297,9 +297,12 @@ enum {
 
 #define EROFS_NAME_LEN      255
 
-/* maximum supported size of a physical compression cluster */
+/* maximum supported encoded size of a physical compressed cluster */
 #define Z_EROFS_PCLUSTER_MAX_SIZE	(1024 * 1024)
 
+/* maximum supported decoded size of a physical compressed cluster */
+#define Z_EROFS_PCLUSTER_MAX_DSIZE	(12 * 1024 * 1024)
+
 /* available compression algorithm types (for h_algorithmtype) */
 enum {
 	Z_EROFS_COMPRESSION_LZ4		= 0,
diff --git a/lib/zmap.c b/lib/zmap.c
index b84d214..70ff898 100644
--- a/lib/zmap.c
+++ b/lib/zmap.c
@@ -633,30 +633,29 @@ int z_erofs_map_blocks_iter(struct erofs_inode *vi,
 {
 	int err = 0;
 
-	/* when trying to read beyond EOF, leave it unmapped */
-	if (map->m_la >= vi->i_size) {
+	if (map->m_la >= vi->i_size) {	/* post-EOF unmapped extent */
 		map->m_llen = map->m_la + 1 - vi->i_size;
 		map->m_la = vi->i_size;
 		map->m_flags = 0;
-		goto out;
-	}
-
-	err = z_erofs_fill_inode_lazy(vi);
-	if (err)
-		goto out;
-
-	if ((vi->z_advise & Z_EROFS_ADVISE_FRAGMENT_PCLUSTER) &&
-	    !vi->z_tailextent_headlcn) {
-		map->m_la = 0;
-		map->m_llen = vi->i_size;
-		map->m_flags = EROFS_MAP_MAPPED | EROFS_MAP_FULL_MAPPED |
-				EROFS_MAP_FRAGMENT;
-		goto out;
+	} else {
+		err = z_erofs_fill_inode_lazy(vi);
+		if (!err) {
+			if ((vi->z_advise & Z_EROFS_ADVISE_FRAGMENT_PCLUSTER) &&
+			    !vi->z_tailextent_headlcn) {
+				map->m_la = 0;
+				map->m_llen = vi->i_size;
+				map->m_flags = EROFS_MAP_MAPPED |
+					EROFS_MAP_FULL_MAPPED | EROFS_MAP_FRAGMENT;
+			} else {
+				err = z_erofs_do_map_blocks(vi, map, flags);
+			}
+		}
+		if (!err && (map->m_flags & EROFS_MAP_ENCODED) &&
+		    __erofs_unlikely(map->m_plen > Z_EROFS_PCLUSTER_MAX_SIZE ||
+				     map->m_llen > Z_EROFS_PCLUSTER_MAX_DSIZE))
+			err = -EOPNOTSUPP;
+		if (err)
+			map->m_llen = 0;
 	}
-
-	err = z_erofs_do_map_blocks(vi, map, flags);
-out:
-	if (err)
-		map->m_llen = 0;
 	return err;
 }
-- 
2.43.5