sd-journal: detect earlier if we try to read an object from an invalid offset

Specifically, detect early if we try to read from offset 0, i.e. are using
uninitialized offset data.

diff --git a/src/journal/journal-file.c b/src/journal/journal-file.c
index ac6c30f..c431863 100644 (file)
--- a/src/journal/journal-file.c
+++ b/src/journal/journal-file.c
@@ -709,6 +709,10 @@ int journal_file_move_to_object(JournalFile *f, ObjectType type, uint64_t offset
         if (!VALID64(offset))
                 return -EFAULT;
 
+        /* Object may not be located in the file header */
+        if (offset < le64toh(f->header->header_size))
+                return -EBADMSG;
+
         r = journal_file_move_to(f, type, false, offset, sizeof(ObjectHeader), &t);
         if (r < 0)
                 return r;