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From e1c0a986e39ab93954436bcf6e6a9a7ea465e4e7 Mon Sep 17 00:00:00 2001
From: Daniel Axtens <dja@axtens.net>
Date: Tue, 6 Jul 2021 19:19:11 +1000
Subject: 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]);
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