45 lines
1.4 KiB
Diff
45 lines
1.4 KiB
Diff
From 210245129c932dc9e1c2748d9d35524fb95b5042 Mon Sep 17 00:00:00 2001
|
|
From: Daniel Axtens <dja@axtens.net>
|
|
Date: Tue, 6 Jul 2021 23:25:07 +1000
|
|
Subject: video/readers/png: Avoid heap OOB R/W inserting huff table items
|
|
|
|
In fuzzing we observed crashes where a code would attempt to be inserted
|
|
into a huffman table before the start, leading to a set of heap OOB reads
|
|
and writes as table entries with negative indices were shifted around and
|
|
the new code written in.
|
|
|
|
Catch the case where we would underflow the array and bail.
|
|
|
|
Fixes: CVE-2021-3696
|
|
|
|
Reference:https://git.savannah.gnu.org/cgit/grub.git/commit/?id=210245129c932dc9e1c2748d9d35524fb95b5042
|
|
Conflict:NA
|
|
|
|
Signed-off-by: Daniel Axtens <dja@axtens.net>
|
|
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
|
|
---
|
|
grub-core/video/readers/png.c | 7 +++++++
|
|
1 file changed, 7 insertions(+)
|
|
|
|
diff --git a/grub-core/video/readers/png.c b/grub-core/video/readers/png.c
|
|
index a3161e2..d7ed5aa 100644
|
|
--- a/grub-core/video/readers/png.c
|
|
+++ b/grub-core/video/readers/png.c
|
|
@@ -438,6 +438,13 @@ grub_png_insert_huff_item (struct huff_table *ht, int code, int len)
|
|
for (i = len; i < ht->max_length; i++)
|
|
n += ht->maxval[i];
|
|
|
|
+ if (n > ht->num_values)
|
|
+ {
|
|
+ grub_error (GRUB_ERR_BAD_FILE_TYPE,
|
|
+ "png: out of range inserting huffman table item");
|
|
+ return;
|
|
+ }
|
|
+
|
|
for (i = 0; i < n; i++)
|
|
ht->values[ht->num_values - i] = ht->values[ht->num_values - i - 1];
|
|
|
|
--
|
|
cgit v1.1
|
|
|