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u-boot: patch for CVE-2018-1000205

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(From OE-Core rev: a8db39548d9985962e4f8764b10856af5226d210)

Signed-off-by: Changqing Li <changqing.li@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
This commit is contained in:
Changqing Li
2018-08-22 13:36:57 +08:00
committed by Richard Purdie
parent fa3529e117
commit f99a77a2db
3 changed files with 206 additions and 1 deletions
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59
meta/recipes-bsp/u-boot/files/CVE-2018-1000205-1.patch Normal file
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@@ -0,0 +1,59 @@
From 7346c1e192d63cd35f99c7e845e53c5d4d0bdc24 Mon Sep 17 00:00:00 2001
From: Teddy Reed <teddy.reed@gmail.com>
Date: Sat, 9 Jun 2018 11:45:20 -0400
Subject: [PATCH] vboot: Do not use hashed-strings offset
The hashed-strings signature property includes two uint32_t values.
The first is unneeded as there should never be a start offset into the
strings region. The second, the size, is needed because the added
signature node appends to this region.
See tools/image-host.c, where a static 0 value is used for the offset.
Signed-off-by: Teddy Reed <teddy.reed@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Upstream-Status: Backport[http://git.denx.de/?p=u-boot.git;a=commit;
h=7346c1e192d63cd35f99c7e845e53c5d4d0bdc24]
CVE: CVE-2018-1000205
Signed-off-by: Changqing Li <changqing.li@windriver.com>
---
common/image-sig.c | 7 +++++--
tools/image-host.c | 1 +
2 files changed, 6 insertions(+), 2 deletions(-)
diff --git a/common/image-sig.c b/common/image-sig.c
index 8d2fd10..5a269d3 100644
--- a/common/image-sig.c
+++ b/common/image-sig.c
@@ -377,8 +377,11 @@ int fit_config_check_sig(const void *fit, int noffset, int required_keynode,
/* Add the strings */
strings = fdt_getprop(fit, noffset, "hashed-strings", NULL);
if (strings) {
- fdt_regions[count].offset = fdt_off_dt_strings(fit) +
- fdt32_to_cpu(strings[0]);
+ /*
+ * The strings region offset must be a static 0x0.
+ * This is set in tool/image-host.c
+ */
+ fdt_regions[count].offset = fdt_off_dt_strings(fit);
fdt_regions[count].size = fdt32_to_cpu(strings[1]);
count++;
}
diff --git a/tools/image-host.c b/tools/image-host.c
index 8e43671..be2d59b 100644
--- a/tools/image-host.c
+++ b/tools/image-host.c
@@ -135,6 +135,7 @@ static int fit_image_write_sig(void *fit, int noffset, uint8_t *value,
ret = fdt_setprop(fit, noffset, "hashed-nodes",
region_prop, region_proplen);
+ /* This is a legacy offset, it is unused, and must remain 0. */
strdata[0] = 0;
strdata[1] = cpu_to_fdt32(string_size);
if (!ret) {
--
2.7.4

143
meta/recipes-bsp/u-boot/files/CVE-2018-1000205-2.patch Normal file
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@@ -0,0 +1,143 @@
From 72239fc85f3eda078547956608c063ab965e90e9 Mon Sep 17 00:00:00 2001
From: Teddy Reed <teddy.reed@gmail.com>
Date: Sat, 9 Jun 2018 11:38:05 -0400
Subject: [PATCH] vboot: Add FIT_SIGNATURE_MAX_SIZE protection
This adds a new config value FIT_SIGNATURE_MAX_SIZE, which controls the
max size of a FIT header's totalsize field. The field is checked before
signature checks are applied to protect from reading past the intended
FIT regions.
This field is not part of the vboot signature so it should be sanity
checked. If the field is corrupted then the structure or string region
reads may have unintended behavior, such as reading from device memory.
A default value of 256MB is set and intended to support most max storage
sizes.
Suggested-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Teddy Reed <teddy.reed@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Upstream-Status: Backport[http://git.denx.de/?p=u-boot.git;a=commit;
h=72239fc85f3eda078547956608c063ab965e90e9]
CVE: CVE-2018-1000205
Signed-off-by: Changqing Li <changqing.li@windriver.com>
---
Kconfig | 10 ++++++++++
common/image-sig.c | 5 +++++
test/py/tests/test_vboot.py | 33 +++++++++++++++++++++++++++++++++
tools/Makefile | 1 +
4 files changed, 49 insertions(+)
diff --git a/Kconfig b/Kconfig
index 5a82c95..c8b86cd 100644
--- a/Kconfig
+++ b/Kconfig
@@ -267,6 +267,16 @@ config FIT_SIGNATURE
format support in this case, enable it using
CONFIG_IMAGE_FORMAT_LEGACY.
+config FIT_SIGNATURE_MAX_SIZE
+ hex "Max size of signed FIT structures"
+ depends on FIT_SIGNATURE
+ default 0x10000000
+ help
+ This option sets a max size in bytes for verified FIT uImages.
+ A sane value of 256MB protects corrupted DTB structures from overlapping
+ device memory. Assure this size does not extend past expected storage
+ space.
+
config FIT_VERBOSE
bool "Show verbose messages when FIT images fail"
help
diff --git a/common/image-sig.c b/common/image-sig.c
index f65d883..8d2fd10 100644
--- a/common/image-sig.c
+++ b/common/image-sig.c
@@ -156,6 +156,11 @@ static int fit_image_setup_verify(struct image_sign_info *info,
{
char *algo_name;
+ if (fdt_totalsize(fit) > CONFIG_FIT_SIGNATURE_MAX_SIZE) {
+ *err_msgp = "Total size too large";
+ return 1;
+ }
+
if (fit_image_hash_get_algo(fit, noffset, &algo_name)) {
*err_msgp = "Can't get hash algo property";
return -1;
diff --git a/test/py/tests/test_vboot.py b/test/py/tests/test_vboot.py
index ee939f2..3d25ec3 100644
--- a/test/py/tests/test_vboot.py
+++ b/test/py/tests/test_vboot.py
@@ -26,6 +26,7 @@ Tests run with both SHA1 and SHA256 hashing.
import pytest
import sys
+import struct
import u_boot_utils as util
@pytest.mark.boardspec('sandbox')
@@ -105,6 +106,26 @@ def test_vboot(u_boot_console):
util.run_and_log(cons, [mkimage, '-F', '-k', tmpdir, '-K', dtb,
'-r', fit])
+ def replace_fit_totalsize(size):
+ """Replace FIT header's totalsize with something greater.
+
+ The totalsize must be less than or equal to FIT_SIGNATURE_MAX_SIZE.
+ If the size is greater, the signature verification should return false.
+
+ Args:
+ size: The new totalsize of the header
+
+ Returns:
+ prev_size: The previous totalsize read from the header
+ """
+ total_size = 0
+ with open(fit, 'r+b') as handle:
+ handle.seek(4)
+ total_size = handle.read(4)
+ handle.seek(4)
+ handle.write(struct.pack(">I", size))
+ return struct.unpack(">I", total_size)[0]
+
def test_with_algo(sha_algo):
"""Test verified boot with the given hash algorithm.
@@ -146,6 +167,18 @@ def test_vboot(u_boot_console):
util.run_and_log(cons, [fit_check_sign, '-f', fit, '-k', tmpdir,
'-k', dtb])
+ # Replace header bytes
+ bcfg = u_boot_console.config.buildconfig
+ max_size = int(bcfg.get('config_fit_signature_max_size', 0x10000000), 0)
+ existing_size = replace_fit_totalsize(max_size + 1)
+ run_bootm(sha_algo, 'Signed config with bad hash', 'Bad Data Hash', False)
+ cons.log.action('%s: Check overflowed FIT header totalsize' % sha_algo)
+
+ # Replace with existing header bytes
+ replace_fit_totalsize(existing_size)
+ run_bootm(sha_algo, 'signed config', 'dev+', True)
+ cons.log.action('%s: Check default FIT header totalsize' % sha_algo)
+
# Increment the first byte of the signature, which should cause failure
sig = util.run_and_log(cons, 'fdtget -t bx %s %s value' %
(fit, sig_node))
diff --git a/tools/Makefile b/tools/Makefile
index 5dd33ed..0c3341e 100644
--- a/tools/Makefile
+++ b/tools/Makefile
@@ -133,6 +133,7 @@ ifdef CONFIG_FIT_SIGNATURE
# This affects include/image.h, but including the board config file
# is tricky, so manually define this options here.
HOST_EXTRACFLAGS += -DCONFIG_FIT_SIGNATURE
+HOST_EXTRACFLAGS += -DCONFIG_FIT_SIGNATURE_MAX_SIZE=$(CONFIG_FIT_SIGNATURE_MAX_SIZE)
endif
ifdef CONFIG_SYS_U_BOOT_OFFS
--
2.7.4

5
meta/recipes-bsp/u-boot/u-boot-common_2018.07.inc
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@@ -10,6 +10,9 @@ PE = "1"
# repo during parse
SRCREV = "8c5d4fd0ec222701598a27b26ab7265d4cee45a3"
SRC_URI = "git://git.denx.de/u-boot.git"
SRC_URI = "git://git.denx.de/u-boot.git \
file://CVE-2018-1000205-1.patch \
file://CVE-2018-1000205-2.patch \
"
S = "${WORKDIR}/git"