python-pyasn1-0.3.7-6.el8_10.1
- Resolves: RHEL-148145 Signed-off-by: Masahiro Matsuya <mmatsuya@redhat.com>
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Masahiro Matsuya
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122
0001-Backport-commit-be353d7.patch
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122
0001-Backport-commit-be353d7.patch
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From b111e63bd3b86ca9747b1bbb3f7eae7b9c01a82e Mon Sep 17 00:00:00 2001
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From: Masahiro Matsuya <mmatsuya@redhat.com>
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Date: Wed, 18 Feb 2026 13:54:42 +0900
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Subject: [PATCH] Backport commit be353d7
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Add limit of 20 continuation octets per OID arc to prevent a potential memory
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exhaustion from excessive continuation bytes input.
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---
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pyasn1/codec/ber/decoder.py | 11 ++++++
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tests/codec/ber/test_decoder.py | 66 +++++++++++++++++++++++++++++++++
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2 files changed, 77 insertions(+)
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diff --git a/pyasn1/codec/ber/decoder.py b/pyasn1/codec/ber/decoder.py
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index ee3064f..69c9ecd 100644
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--- a/pyasn1/codec/ber/decoder.py
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+++ b/pyasn1/codec/ber/decoder.py
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@@ -14,6 +14,10 @@ __all__ = ['decode']
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noValue = base.noValue
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+# Maximum number of continuation octets (high-bit set) allowed per OID arc.
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+# 20 octets allows up to 140-bit integers, supporting UUID-based OIDs
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+MAX_OID_ARC_CONTINUATION_OCTETS = 20
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+
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class AbstractDecoder(object):
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protoComponent = None
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@@ -284,7 +288,14 @@ class ObjectIdentifierDecoder(AbstractSimpleDecoder):
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# Construct subid from a number of octets
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nextSubId = subId
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subId = 0
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+ continuationOctetCount = 0
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while nextSubId >= 128:
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+ continuationOctetCount += 1
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+ if continuationOctetCount > MAX_OID_ARC_CONTINUATION_OCTETS:
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+ raise error.PyAsn1Error(
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+ 'OID arc exceeds maximum continuation octets limit (%d) '
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+ 'at position %d' % (MAX_OID_ARC_CONTINUATION_OCTETS, index)
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+ )
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subId = (subId << 7) + (nextSubId & 0x7F)
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if index >= substrateLen:
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raise error.SubstrateUnderrunError(
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diff --git a/tests/codec/ber/test_decoder.py b/tests/codec/ber/test_decoder.py
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index 5ec3a5f..ba7dfec 100644
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--- a/tests/codec/ber/test_decoder.py
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+++ b/tests/codec/ber/test_decoder.py
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@@ -403,6 +403,72 @@ class ObjectIdentifierDecoderTestCase(BaseTestCase):
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0xB8, 0xCB, 0xE2, 0xB6, 0x47))
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) == ((2, 999, 18446744073709551535184467440737095), null)
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+ def testExcessiveContinuationOctets(self):
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+ """Test that OID arcs with excessive continuation octets are rejected."""
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+ # Create a payload with 25 continuation octets (exceeds 20 limit)
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+ # 0x81 bytes are continuation octets, 0x01 terminates
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+ malicious_payload = bytes([0x06, 26]) + bytes([0x81] * 25) + bytes([0x01])
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+ try:
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+ decoder.decode(malicious_payload)
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+ except PyAsn1Error:
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+ pass
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+ else:
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+ assert 0, 'Excessive continuation octets tolerated'
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+
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+ def testMaxAllowedContinuationOctets(self):
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+ """Test that OID arcs at the maximum continuation octets limit work."""
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+ # Create a payload with exactly 20 continuation octets (at limit)
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+ # This should succeed
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+ payload = bytes([0x06, 21]) + bytes([0x81] * 20) + bytes([0x01])
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+ try:
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+ decoder.decode(payload)
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+ except PyAsn1Error:
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+ assert 0, 'Valid OID with 20 continuation octets rejected'
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+
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+ def testOneOverContinuationLimit(self):
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+ """Test boundary: 21 continuation octets (one over limit) is rejected."""
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+ payload = bytes([0x06, 22]) + bytes([0x81] * 21) + bytes([0x01])
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+ try:
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+ decoder.decode(payload)
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+ except PyAsn1Error:
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+ pass
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+ else:
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+ assert 0, '21 continuation octets tolerated (should be rejected)'
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+
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+ def testExcessiveContinuationInSecondArc(self):
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+ """Test that limit applies to subsequent arcs, not just the first."""
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+ # First arc: valid simple byte (0x55 = 85, decodes to arc 2.5)
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+ # Second arc: excessive continuation octets
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+ payload = bytes([0x06, 27]) + bytes([0x55]) + bytes([0x81] * 25) + bytes([0x01])
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+ try:
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+ decoder.decode(payload)
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+ except PyAsn1Error:
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+ pass
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+ else:
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+ assert 0, 'Excessive continuation in second arc tolerated'
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+
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+ def testMultipleArcsAtLimit(self):
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+ """Test multiple arcs each at the continuation limit work correctly."""
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+ # Two arcs, each with 20 continuation octets (both at limit)
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+ arc1 = bytes([0x81] * 20) + bytes([0x01]) # 21 bytes
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+ arc2 = bytes([0x81] * 20) + bytes([0x01]) # 21 bytes
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+ payload = bytes([0x06, 42]) + arc1 + arc2
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+ try:
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+ decoder.decode(payload)
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+ except PyAsn1Error:
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+ assert 0, 'Multiple valid arcs at limit rejected'
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+
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+ def testExcessiveContinuationWithMaxBytes(self):
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+ """Test with 0xFF continuation bytes (maximum value, not just 0x81)."""
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+ # 0xFF bytes are also continuation octets (high bit set)
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+ malicious_payload = bytes([0x06, 26]) + bytes([0xFF] * 25) + bytes([0x01])
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+ try:
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+ decoder.decode(malicious_payload)
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+ except PyAsn1Error:
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+ pass
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+ else:
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+ assert 0, 'Excessive 0xFF continuation octets tolerated'
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+
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class RealDecoderTestCase(BaseTestCase):
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def testChar(self):
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--
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2.52.0
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@ -3,7 +3,7 @@
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Name: python-pyasn1
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Version: 0.3.7
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Release: 6%{?dist}
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Release: 6%{?dist}.1
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Summary: ASN.1 tools for Python
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License: BSD
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Group: System Environment/Libraries
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@ -12,6 +12,9 @@ Source1: https://github.com/etingof/pyasn1-modules/archive/v%{modules_ver
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URL: http://pyasn1.sourceforge.net/
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BuildArch: noarch
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Patch1: 0001-Backport-commit-be353d7.patch
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%description
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This is an implementation of ASN.1 types and codecs in the Python programming
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language.
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@ -44,6 +47,7 @@ BuildRequires: python3-sphinx
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%prep
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%setup -n %{module}-%{version} -q -b1
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%autopatch -p1
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%build
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@ -85,6 +89,9 @@ PYTHONPATH=%{buildroot}%{python3_sitelib} %{__python3} setup.py test
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%doc doc/build/html/*
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%changelog
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* Wed Feb 18 2026 Masahiro Matsuya <mmatsuya@redhat.com> - 0.3.7-6.el8_10.1
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- Resolves: RHEL-148145
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* Mon Jul 09 2018 Petr Viktorin <pviktori@redhat.com> - 0.3.7-6
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- Remove the python2 subpackage
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