jbd2: Fail to load a journal if it is too short

Due to on disk corruption, it can happen that journal is too short. Fail
to load it in such case so that we don't oops somewhere later.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 6 insertions, 0 deletions

diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index e378cb383979..a8a358bc0f21 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -1187,6 +1187,12 @@ static int journal_reset(journal_t *journal)
 
         first = be32_to_cpu(sb->s_first);
         last = be32_to_cpu(sb->s_maxlen);
+        if (first + JBD2_MIN_JOURNAL_BLOCKS > last + 1) {
+                printk(KERN_ERR "JBD: Journal too short (blocks %llu-%llu).\n",
+                       first, last);
+                journal_fail_superblock(journal);
+                return -EINVAL;
+        }
 
         journal->j_first = first;
         journal->j_last = last;