[PATCH] ext2fs: Add a basic bounds check to journal superblock load.

[Milos Nikic]

If it has been corrupted on disk, we should not use it.
---
 ext2fs/journal.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/ext2fs/journal.c b/ext2fs/journal.c
index 99268cf75..2625ea327 100644
--- a/ext2fs/journal.c
+++ b/ext2fs/journal.c
@@ -888,6 +888,16 @@ journal_load_superblock (journal_t *journal)
       free (buf);
       return EINVAL;
     }
+  if (journal->j_first >= journal->map.total_blocks ||
+      journal->j_head >= journal->map.total_blocks)
+    {
+      JRNL_LOG_WARN
+       ("Superblock bounds corrupted! First: %u, Head: %u, Max: %u",
+        journal->j_first, journal->j_head, journal->map.total_blocks);
+      free (buf);
+      return EINVAL;
+    }
+
   jsb->s_maxlen = htobe32 (journal->map.total_blocks);
 
   journal->j_sb_buffer = buf;
-- 
2.54.0