From 690bee69fae6b4bd911293d6b7e56774e29fdf64 Mon Sep 17 00:00:00 2001

From: Daniel Axtens <dja@axtens.net>

Date: Tue, 6 Jul 2021 19:19:11 +1000

Subject: [PATCH 4/8] video/readers/png: Sanity check some huffman codes

ASAN picked up two OOB global reads: we weren't checking if some code

values fit within the cplens or cpdext arrays. Check and throw an error

if not.

Signed-off-by: Daniel Axtens <dja@axtens.net>

Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

---

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

 1 file changed, 6 insertions(+)

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

index d7ed5aa6c..7f2ba7849 100644

--- a/grub-core/video/readers/png.c

+++ b/grub-core/video/readers/png.c

@@ -753,6 +753,9 @@ grub_png_read_dynamic_block (struct grub_png_data *data)

 	  int len, dist, pos;

 	  n -= 257;

+	  if (((unsigned int) n) >= ARRAY_SIZE (cplens))

+	    return grub_error (GRUB_ERR_BAD_FILE_TYPE,

+			       "png: invalid huff code");

 	  len = cplens[n];

 	  if (cplext[n])

 	    len += grub_png_get_bits (data, cplext[n]);

@@ -760,6 +763,9 @@ grub_png_read_dynamic_block (struct grub_png_data *data)

 	    return grub_errno;

 	  n = grub_png_get_huff_code (data, &data->dist_table);

+	  if (((unsigned int) n) >= ARRAY_SIZE (cpdist))

+	    return grub_error (GRUB_ERR_BAD_FILE_TYPE,

+			       "png: invalid huff code");

 	  dist = cpdist[n];

 	  if (cpdext[n])

 	    dist += grub_png_get_bits (data, cpdext[n]);

-- 

2.33.5