In exfat_find_last_cluster(), the cluster chain is traversed until the EOF cluster. If the cluster chain includes a loop due to file system corruption, the EOF cluster cannot be traversed, resulting in an infinite loop. If the number of clusters indicated by the file size is inconsistent with the cluster chain length, exfat_find_last_cluster() will return an error, so if this inconsistency is found, the traversal can be aborted without traversing to the EOF cluster. Reported-by: syzbot+f7d147e6db52b1e09dba@xxxxxxxxxxxxxxxxxxxxxxxxx Closes: https://syzkaller.appspot.com/bug?extid=f7d147e6db52b1e09dba Tested-by: syzbot+f7d147e6db52b1e09dba@xxxxxxxxxxxxxxxxxxxxxxxxx Fixes: 31023864e67a ("exfat: add fat entry operations") Signed-off-by: Yuezhang Mo <Yuezhang.Mo@xxxxxxxx> --- fs/exfat/fatent.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/exfat/fatent.c b/fs/exfat/fatent.c index b9473a69f104..23065f948ae7 100644 --- a/fs/exfat/fatent.c +++ b/fs/exfat/fatent.c @@ -294,7 +294,7 @@ int exfat_find_last_cluster(struct super_block *sb, struct exfat_chain *p_chain, clu = next; if (exfat_ent_get(sb, clu, &next)) return -EIO; - } while (next != EXFAT_EOF_CLUSTER); + } while (next != EXFAT_EOF_CLUSTER && count <= p_chain->size); if (p_chain->size != count) { exfat_fs_error(sb, -- 2.43.0
