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grub2: Fix buffer underflow write in the heap

Browse Source 
Source: https://git.savannah.gnu.org/gitweb/?p=grub.git
MR: 119719, 119733, 119689
Type: Security Fix
Disposition: Backport from https://git.savannah.gnu.org/gitweb/?p=grub.git;a=commit;h=e623866d9286410156e8b9d2c82d6253a1b22d08 && https://git.savannah.gnu.org/gitweb/?p=grub.git;a=commit;h=210245129c932dc9e1c2748d9d35524fb95b5042 && https://git.savannah.gnu.org/gitweb/?p=grub.git;a=commit;h=22a3f97d39f6a10b08ad7fd1cc47c4dcd10413f6
ChangeID: 97605970cd42776fa449fd8318f2762e32bbd177
Description:
Fixed CVEs :
        CVE-2021-3695
        CVE-2021-3696
        CVE-2021-3697

Affects "grub2 < 2.06"

(From OE-Core rev: 191db3c58b52fa7c8530d82f7e3e3b24075fdeb4)

Signed-off-by: Hitendra Prajapati <hprajapati@mvista.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
This commit is contained in:
Hitendra Prajapati
2022-07-26 12:34:02 +05:30
committed by Richard Purdie
parent e4946bd39e
commit 9e7f4a7db2
4 changed files with 310 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

178
meta/recipes-bsp/grub/files/CVE-2021-3695.patch Normal file
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@@ -0,0 +1,178 @@
From 0693d672abcf720419f86c56bda6428c540e2bb1 Mon Sep 17 00:00:00 2001
From: Hitendra Prajapati <hprajapati@mvista.com>
Date: Wed, 20 Jul 2022 10:01:35 +0530
Subject: [PATCH] CVE-2021-3695
Upstream-Status: Backport [https://git.savannah.gnu.org/gitweb/?p=grub.git;a=commit;h=e623866d9286410156e8b9d2c82d6253a1b22d08]
CVE: CVE-2021-3695
Signed-off-by: Hitendra Prajapati <hprajapati@mvista.com>
video/readers/png: Drop greyscale support to fix heap out-of-bounds write
A 16-bit greyscale PNG without alpha is processed in the following loop:
for (i = 0; i < (data->image_width * data->image_height);
i++, d1 += 4, d2 += 2)
{
d1[R3] = d2[1];
d1[G3] = d2[1];
d1[B3] = d2[1];
}
The increment of d1 is wrong. d1 is incremented by 4 bytes per iteration,
but there are only 3 bytes allocated for storage. This means that image
data will overwrite somewhat-attacker-controlled parts of memory - 3 bytes
out of every 4 following the end of the image.
This has existed since greyscale support was added in 2013 in commit
3ccf16dff98f (grub-core/video/readers/png.c: Support grayscale).
Saving starfield.png as a 16-bit greyscale image without alpha in the gimp
and attempting to load it causes grub-emu to crash - I don't think this code
has ever worked.
Delete all PNG greyscale support.
Fixes: CVE-2021-3695
Signed-off-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
---
grub-core/video/readers/png.c | 89 ++++-------------------------------
1 file changed, 8 insertions(+), 81 deletions(-)
diff --git a/grub-core/video/readers/png.c b/grub-core/video/readers/png.c
index 0157ff7..db4a9d4 100644
--- a/grub-core/video/readers/png.c
+++ b/grub-core/video/readers/png.c
@@ -100,7 +100,7 @@ struct grub_png_data
unsigned image_width, image_height;
int bpp, is_16bit;
- int raw_bytes, is_gray, is_alpha, is_palette;
+ int raw_bytes, is_alpha, is_palette;
int row_bytes, color_bits;
grub_uint8_t *image_data;
@@ -280,13 +280,13 @@ grub_png_decode_image_header (struct grub_png_data *data)
data->bpp = 3;
else
{
- data->is_gray = 1;
- data->bpp = 1;
+ return grub_error (GRUB_ERR_BAD_FILE_TYPE,
+ "png: color type not supported");
}
if ((color_bits != 8) && (color_bits != 16)
&& (color_bits != 4
- || !(data->is_gray || data->is_palette)))
+ || !data->is_palette))
return grub_error (GRUB_ERR_BAD_FILE_TYPE,
"png: bit depth must be 8 or 16");
@@ -315,7 +315,7 @@ grub_png_decode_image_header (struct grub_png_data *data)
}
#ifndef GRUB_CPU_WORDS_BIGENDIAN
- if (data->is_16bit || data->is_gray || data->is_palette)
+ if (data->is_16bit || data->is_palette)
#endif
{
data->image_data = grub_calloc (data->image_height, data->row_bytes);
@@ -859,27 +859,8 @@ grub_png_convert_image (struct grub_png_data *data)
int shift;
int mask = (1 << data->color_bits) - 1;
unsigned j;
- if (data->is_gray)
- {
- /* Generic formula is
- (0xff * i) / ((1U << data->color_bits) - 1)
- but for allowed bit depth of 1, 2 and for it's
- equivalent to
- (0xff / ((1U << data->color_bits) - 1)) * i
- Precompute the multipliers to avoid division.
- */
-
- const grub_uint8_t multipliers[5] = { 0xff, 0xff, 0x55, 0x24, 0x11 };
- for (i = 0; i < (1U << data->color_bits); i++)
- {
- grub_uint8_t col = multipliers[data->color_bits] * i;
- palette[i][0] = col;
- palette[i][1] = col;
- palette[i][2] = col;
- }
- }
- else
- grub_memcpy (palette, data->palette, 3 << data->color_bits);
+
+ grub_memcpy (palette, data->palette, 3 << data->color_bits);
d1c = d1;
d2c = d2;
for (j = 0; j < data->image_height; j++, d1c += data->image_width * 3,
@@ -917,61 +898,7 @@ grub_png_convert_image (struct grub_png_data *data)
return;
}
- if (data->is_gray)
- {
- switch (data->bpp)
- {
- case 4:
- /* 16-bit gray with alpha. */
- for (i = 0; i < (data->image_width * data->image_height);
- i++, d1 += 4, d2 += 4)
- {
- d1[R4] = d2[3];
- d1[G4] = d2[3];
- d1[B4] = d2[3];
- d1[A4] = d2[1];
- }
- break;
- case 2:
- if (data->is_16bit)
- /* 16-bit gray without alpha. */
- {
- for (i = 0; i < (data->image_width * data->image_height);
- i++, d1 += 4, d2 += 2)
- {
- d1[R3] = d2[1];
- d1[G3] = d2[1];
- d1[B3] = d2[1];
- }
- }
- else
- /* 8-bit gray with alpha. */
- {
- for (i = 0; i < (data->image_width * data->image_height);
- i++, d1 += 4, d2 += 2)
- {
- d1[R4] = d2[1];
- d1[G4] = d2[1];
- d1[B4] = d2[1];
- d1[A4] = d2[0];
- }
- }
- break;
- /* 8-bit gray without alpha. */
- case 1:
- for (i = 0; i < (data->image_width * data->image_height);
- i++, d1 += 3, d2++)
- {
- d1[R3] = d2[0];
- d1[G3] = d2[0];
- d1[B3] = d2[0];
- }
- break;
- }
- return;
- }
-
- {
+ {
/* Only copy the upper 8 bit. */
#ifndef GRUB_CPU_WORDS_BIGENDIAN
for (i = 0; i < (data->image_width * data->image_height * data->bpp >> 1);
--
2.25.1

46
meta/recipes-bsp/grub/files/CVE-2021-3696.patch Normal file
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@@ -0,0 +1,46 @@
From b18ce59d6496a9313d75f9497a0efac61dcf4191 Mon Sep 17 00:00:00 2001
From: Hitendra Prajapati <hprajapati@mvista.com>
Date: Wed, 20 Jul 2022 10:05:42 +0530
Subject: [PATCH] CVE-2021-3696
Upstream-Status: Backport [https://git.savannah.gnu.org/gitweb/?p=grub.git;a=commit;h=210245129c932dc9e1c2748d9d35524fb95b5042]
CVE: CVE-2021-3696
Signed-off-by: Hitendra Prajapati <hprajapati@mvista.com>
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
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 36b3f10..3c05951 100644
--- a/grub-core/video/readers/png.c
+++ b/grub-core/video/readers/png.c
@@ -416,6 +416,13 @@ 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];
--
2.25.1

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@@ -0,0 +1,82 @@
From 4de9de9d14f4ac27229e45514627534e32cc4406 Mon Sep 17 00:00:00 2001
From: Hitendra Prajapati <hprajapati@mvista.com>
Date: Tue, 19 Jul 2022 11:13:02 +0530
Subject: [PATCH] CVE-2021-3697
Upstream-Status: Backport [https://git.savannah.gnu.org/gitweb/?p=grub.git;a=commit;h=22a3f97d39f6a10b08ad7fd1cc47c4dcd10413f6]
CVE: CVE-2021-3697
Signed-off-by: Hitendra Prajapati <hprajapati@mvista.com>
video/readers/jpeg: Block int underflow -> wild pointer write
Certain 1 px wide images caused a wild pointer write in
grub_jpeg_ycrcb_to_rgb(). This was caused because in grub_jpeg_decode_data(),
we have the following loop:
for (; data->r1 < nr1 && (!data->dri || rst);
data->r1++, data->bitmap_ptr += (vb * data->image_width - hb * nc1) * 3)
We did not check if vb * width >= hb * nc1.
On a 64-bit platform, if that turns out to be negative, it will underflow,
be interpreted as unsigned 64-bit, then be added to the 64-bit pointer, so
we see data->bitmap_ptr jump, e.g.:
0x6180_0000_0480 to
0x6181_0000_0498
^
~--- carry has occurred and this pointer is now far away from
any object.
On a 32-bit platform, it will decrement the pointer, creating a pointer
that won't crash but will overwrite random data.
Catch the underflow and error out.
Fixes: CVE-2021-3697
Signed-off-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
---
grub-core/video/readers/jpeg.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/grub-core/video/readers/jpeg.c b/grub-core/video/readers/jpeg.c
index 31359a4..545a60b 100644
--- a/grub-core/video/readers/jpeg.c
+++ b/grub-core/video/readers/jpeg.c
@@ -23,6 +23,7 @@
#include <grub/mm.h>
#include <grub/misc.h>
#include <grub/bufio.h>
+#include <grub/safemath.h>
GRUB_MOD_LICENSE ("GPLv3+");
@@ -617,6 +618,7 @@ static grub_err_t
grub_jpeg_decode_data (struct grub_jpeg_data *data)
{
unsigned c1, vb, hb, nr1, nc1;
+ unsigned stride_a, stride_b, stride;
int rst = data->dri;
vb = 8 << data->log_vs;
@@ -624,8 +626,14 @@ grub_jpeg_decode_data (struct grub_jpeg_data *data)
nr1 = (data->image_height + vb - 1) >> (3 + data->log_vs);
nc1 = (data->image_width + hb - 1) >> (3 + data->log_hs);
+ if (grub_mul(vb, data->image_width, &stride_a) ||
+ grub_mul(hb, nc1, &stride_b) ||
+ grub_sub(stride_a, stride_b, &stride))
+ return grub_error (GRUB_ERR_BAD_FILE_TYPE,
+ "jpeg: cannot decode image with these dimensions");
+
for (; data->r1 < nr1 && (!data->dri || rst);
- data->r1++, data->bitmap_ptr += (vb * data->image_width - hb * nc1) * 3)
+ data->r1++, data->bitmap_ptr += stride * 3)
for (c1 = 0; c1 < nc1 && (!data->dri || rst);
c1++, rst--, data->bitmap_ptr += hb * 3)
{
--
2.25.1

5
meta/recipes-bsp/grub/grub2.inc
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@@ -95,7 +95,10 @@ SRC_URI = "${GNU_MIRROR}/grub/grub-${PV}.tar.gz \
file://0044-script-execute-Fix-NULL-dereference-in-grub_script_e.patch \
file://0045-commands-ls-Require-device_name-is-not-NULL-before-p.patch \
file://0046-script-execute-Avoid-crash-when-using-outside-a-func.patch \
file://CVE-2021-3981.patch\
file://CVE-2021-3981.patch \
file://CVE-2021-3695.patch \
file://CVE-2021-3696.patch \
file://CVE-2021-3697.patch \
"
SRC_URI[md5sum] = "5ce674ca6b2612d8939b9e6abed32934"
SRC_URI[sha256sum] = "f10c85ae3e204dbaec39ae22fa3c5e99f0665417e91c2cb49b7e5031658ba6ea"