From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001

From: Darren Kenny <darren.kenny@oracle.com>

Date: Fri, 4 Dec 2020 15:39:00 +0000

Subject: [PATCH] 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>

---

 grub-core/video/readers/jpeg.c | 6 ++++++

 1 file changed, 6 insertions(+)

diff --git a/grub-core/video/readers/jpeg.c b/grub-core/video/readers/jpeg.c

index 31359a4c9..0b6ce3cee 100644

--- 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)

     {