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fit: Don't allow verification of images with @ nodes

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When searching for a node called 'fred', any unit address appended to the
name is ignored by libfdt, meaning that 'fred' can match 'fred@1'. This
means that we cannot be sure that the node originally intended is the one
that is used.

Disallow use of nodes with unit addresses.

Update the forge test also, since it uses @ addresses.

CVE-2021-27138

Signed-off-by: Simon Glass <sjg@chromium.org>
Reported-by: Bruce Monroe <bruce.monroe@intel.com>
Reported-by: Arie Haenel <arie.haenel@intel.com>
Reported-by: Julien Lenoir <julien.lenoir@intel.com>
This commit is contained in:
Simon Glass 2021-02-15 17:08:06 -07:00 • committed by Tom Rini
parent 8a7d4cf982
commit 79af75f777
4 changed files with 53 additions and 25 deletions
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12
test/py/tests/vboot_forge.py
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@ -376,12 +376,12 @@ def manipulate(root, strblock):
"""
Maliciously manipulates the structure to create a crafted FIT file
"""
# locate /images/kernel@1 (frankly, it just expects it to be the first one)
# locate /images/kernel-1 (frankly, it just expects it to be the first one)
kernel_node = root[0][0]
# clone it to save time filling all the properties
fake_kernel = kernel_node.clone()
# rename the node
fake_kernel.name = b'kernel@2'
fake_kernel.name = b'kernel-2'
# get rid of signatures/hashes
fake_kernel.children = []
# NOTE: this simply replaces the first prop... either description or data
@ -391,13 +391,13 @@ def manipulate(root, strblock):
root[0].children.append(fake_kernel)
# modify the default configuration
root[1].props[0].value = b'conf@2\x00'
root[1].props[0].value = b'conf-2\x00'
# clone the first (only?) configuration
fake_conf = root[1][0].clone()
# rename and change kernel and fdt properties to select the crafted kernel
fake_conf.name = b'conf@2'
fake_conf.props[0].value = b'kernel@2\x00'
fake_conf.props[1].value = b'fdt@1\x00'
fake_conf.name = b'conf-2'
fake_conf.props[0].value = b'kernel-2\x00'
fake_conf.props[1].value = b'fdt-1\x00'
# insert the new configuration under /configurations
root[1].children.append(fake_conf)