video/readers/jpeg: Test for an invalid next marker reference from a jpeg file

While it may never happen, and potentially could be caught at the end of
the function, it is worth checking up front for a bad reference to the
next marker just in case of a maliciously crafted file being provided.

Fixes: CID 73694
Signed-off-by: Darren Kenny <darren.kenny@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

diff --git a/grub-core/video/readers/jpeg.c b/grub-core/video/readers/jpeg.c
index 31359a4c9c8a5bd289d9d1d620962a3d163d171a..0b6ce3cee6425fb6b07bfde36bf283aaf4318033 100644 (file)
--- a/grub-core/video/readers/jpeg.c
+++ b/grub-core/video/readers/jpeg.c
@@ -253,6 +253,12 @@ grub_jpeg_decode_quan_table (struct grub_jpeg_data *data)
   next_marker = data->file->offset;
   next_marker += grub_jpeg_get_word (data);
 
+  if (next_marker > data->file->size)
+    {
+      /* Should never be set beyond the size of the file. */
+      return grub_error (GRUB_ERR_BAD_FILE_TYPE, "jpeg: invalid next reference");
+    }
+
   while (data->file->offset + sizeof (data->quan_table[id]) + 1
         <= next_marker)
     {