video/readers/jpeg: Do not permit duplicate SOF0 markers in JPEG

Otherwise a subsequent header could change the height and width
allowing future OOB writes.

Fixes: CVE-2024-45774
Reported-by: Nils Langius <nils@langius.de>
Signed-off-by: Daniel Axtens <dja@axtens.net>
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 ae634fd419dfef026d632522b01997ee3d443106..631a893564039e39575de7df76364be31afff5a5 100644 (file)
--- a/grub-core/video/readers/jpeg.c
+++ b/grub-core/video/readers/jpeg.c
@@ -339,6 +339,10 @@ grub_jpeg_decode_sof (struct grub_jpeg_data *data)
   if (grub_errno != GRUB_ERR_NONE)
     return grub_errno;
 
+  if (data->image_height != 0 || data->image_width != 0)
+    return grub_error (GRUB_ERR_BAD_FILE_TYPE,
+                      "jpeg: cannot have duplicate SOF0 markers");
+
   if (grub_jpeg_get_byte (data) != 8)
     return grub_error (GRUB_ERR_BAD_FILE_TYPE,
                       "jpeg: only 8-bit precision is supported");