erofs-utils: lib: handle NONHEAD !delta[1] lclusters gracefully

Source kernel commit: 0bc8061ffc733a0a246b8689b2d32a3e9204f43c

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20250206125034.1462966-6-hsiangkao@linux.alibaba.com

diff --git a/lib/zmap.c b/lib/zmap.c
index cf0a4357d1b1161f8f3d52740e7f7cc33be4149d..23b1bb7add6160f9cae3a2a8524f43ffc185a81a 100644 (file)
--- a/lib/zmap.c
+++ b/lib/zmap.c
@@ -231,7 +231,7 @@ static int z_erofs_load_compact_lcluster(struct z_erofs_maprecorder *m,
        erofs_blk_t eblk;
        int err;
 
-       if (lcn >= totalidx)
+       if (lcn >= totalidx || vi->z_logical_clusterbits > 14)
                return -EINVAL;
 
        m->lcn = lcn;
@@ -415,7 +415,7 @@ static int z_erofs_get_extent_decompressedlen(struct z_erofs_maprecorder *m)
        u64 lcn = m->lcn, headlcn = map->m_la >> lclusterbits;
        int err;
 
-       do {
+       while (1) {
                /* handle the last EOF pcluster (no next HEAD lcluster) */
                if ((lcn << lclusterbits) >= vi->i_size) {
                        map->m_llen = vi->i_size - map->m_la;
@@ -427,14 +427,16 @@ static int z_erofs_get_extent_decompressedlen(struct z_erofs_maprecorder *m)
                        return err;
 
                if (m->type == Z_EROFS_LCLUSTER_TYPE_NONHEAD) {
-                       DBG_BUGON(!m->delta[1] &&
-                                 m->clusterofs != 1 << lclusterbits);
+                       /* work around invalid d1 generated by pre-1.0 mkfs */
+                       if (__erofs_unlikely(!m->delta[1])) {
+                               m->delta[1] = 1;
+                               DBG_BUGON(1);
+                       }
                } else if (m->type == Z_EROFS_LCLUSTER_TYPE_PLAIN ||
                           m->type == Z_EROFS_LCLUSTER_TYPE_HEAD1 ||
                           m->type == Z_EROFS_LCLUSTER_TYPE_HEAD2) {
-                       /* go on until the next HEAD lcluster */
                        if (lcn != headlcn)
-                               break;
+                               break;  /* ends at the next HEAD lcluster */
                        m->delta[1] = 1;
                } else {
                        erofs_err("unknown type %u @ lcn %llu of nid %llu",
@@ -444,8 +446,7 @@ static int z_erofs_get_extent_decompressedlen(struct z_erofs_maprecorder *m)
                        return -EOPNOTSUPP;
                }
                lcn += m->delta[1];
-       } while (m->delta[1]);
-
+       }
        map->m_llen = (lcn << lclusterbits) + m->clusterofs - map->m_la;
        return 0;
 }