ext4: fix potential use after free in __ext4_journal_stop

There is a use-after-free possibility in __ext4_journal_stop() in the case that we free the handle in the first jbd2_journal_stop() because we're referencing handle->h_err afterwards. This was introduced in 9705acd and it is wrong. Fix it by storing the handle->h_err value beforehand and avoid referencing potentially freed handle. Fixes: 9705acd Signed-off-by: Lukas Czerner <[email protected]> Reviewed-by: Andreas Dilger <[email protected]> Cc: [email protected]
ambv · Oct 18, 2015 · 6934da9 · 6934da9
1 parent 33d1497
commit 6934da9
Showing 1 changed file with 3 additions and 3 deletions.
diff --git a/fs/ext4/ext4_jbd2.c b/fs/ext4/ext4_jbd2.c
@@ -88,13 +88,13 @@ int __ext4_journal_stop(const char *where, unsigned int line, handle_t *handle)
 		return 0;
 	}
 
+	err = handle->h_err;
 	if (!handle->h_transaction) {
-		err = jbd2_journal_stop(handle);
-		return handle->h_err ? handle->h_err : err;
+		rc = jbd2_journal_stop(handle);
+		return err ? err : rc;
 	}
 
 	sb = handle->h_transaction->t_journal->j_private;
-	err = handle->h_err;
 	rc = jbd2_journal_stop(handle);
 
 	if (!err)