Re: [syzbot] [erofs?] KASAN: global-out-of-bounds Read in z_erofs_decompress_queue

[Edward Adam Davis]

#syz test

diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
index 2d73297003d2..11f59bc2db8e 100644
--- a/fs/erofs/zdata.c
+++ b/fs/erofs/zdata.c
@@ -752,6 +752,10 @@ static int z_erofs_register_pcluster(struct z_erofs_frontend *fe)
 
 	lockref_init(&pcl->lockref); /* one ref for this request */
 	pcl->algorithmformat = map->m_algorithmformat;
+	if (pcl->algorithmformat >= Z_EROFS_COMPRESSION_MAX) {
+		err = -EINVAL;
+		goto out;
+	}
 	pcl->pclustersize = map->m_plen;
 	pcl->length = 0;
 	pcl->partial = true;
@@ -796,6 +800,7 @@ static int z_erofs_register_pcluster(struct z_erofs_frontend *fe)
 
 err_out:
 	mutex_unlock(&pcl->lock);
+out:
 	z_erofs_free_pcluster(pcl);
 	return err;
 }