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Fix input length checking in SPNEGO DER decoding

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This commit is contained in:
Robbie Harwood 2020-09-09 17:47:18 -04:00
parent 1003328588
commit d7334ebf68
2 changed files with 63 additions and 1 deletions
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58
Fix-input-length-checking-in-SPNEGO-DER-decoding.patch Normal file
View File

@ -0,0 +1,58 @@
From 9504dd4de49938e4cdd56ce6df635b76eaf37e96 Mon Sep 17 00:00:00 2001
From: Greg Hudson <ghudson@mit.edu>
Date: Tue, 28 Jul 2020 12:58:26 -0400
Subject: [PATCH] Fix input length checking in SPNEGO DER decoding
In get_mech_set(), check the length before reading the first byte, and
decrease the length by the tag byte when reading and verifying the
sequence length.
In get_req_flags(), check the length before reading the first byte,
and check the context tag length after decoding it.
ticket: 8933 (new)
tags: pullup
target_version: 1.18-next
target_version: 1.17-next
(cherry picked from commit 64f4b75a22212681ca293f8f09ddd24b0244d5b4)
---
src/lib/gssapi/spnego/spnego_mech.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/src/lib/gssapi/spnego/spnego_mech.c b/src/lib/gssapi/spnego/spnego_mech.c
index 4cf011143..13c351620 100644
--- a/src/lib/gssapi/spnego/spnego_mech.c
+++ b/src/lib/gssapi/spnego/spnego_mech.c
@@ -3462,14 +3462,14 @@ get_mech_set(OM_uint32 *minor_status, unsigned char **buff_in,
unsigned char *start;
int i;
- if (**buff_in != SEQUENCE_OF)
+ if (buff_length < 1 || **buff_in != SEQUENCE_OF)
return (NULL);
start = *buff_in;
(*buff_in)++;
- length = gssint_get_der_length(buff_in, buff_length, &bytes);
- if (length < 0 || buff_length - bytes < (unsigned int)length)
+ length = gssint_get_der_length(buff_in, buff_length - 1, &bytes);
+ if (length < 0 || buff_length - 1 - bytes < (unsigned int)length)
return NULL;
major_status = gss_create_empty_oid_set(minor_status,
@@ -3549,11 +3549,11 @@ get_req_flags(unsigned char **buff_in, OM_uint32 bodysize,
{
unsigned int len;
- if (**buff_in != (CONTEXT | 0x01))
+ if (bodysize < 1 || **buff_in != (CONTEXT | 0x01))
return (0);
if (g_get_tag_and_length(buff_in, (CONTEXT | 0x01),
- bodysize, &len) < 0)
+ bodysize, &len) < 0 || len != 4)
return GSS_S_DEFECTIVE_TOKEN;
if (*(*buff_in)++ != BIT_STRING)

6
krb5.spec
View File

@ -18,7 +18,7 @@ Summary: The Kerberos network authentication system
Name: krb5
Version: 1.18.2
# for prerelease, should be e.g., 0.% {prerelease}.1% { ?dist } (without spaces)
Release: 21%{?dist}
Release: 22%{?dist}
# rharwood has trust path to signing key and verifies on check-in
Source0: https://web.mit.edu/kerberos/dist/krb5/1.18/krb5-%{version}%{prerelease}.tar.gz
@ -71,6 +71,7 @@ Patch32: Use-two-queues-for-concurrent-t_otp.py-daemons.patch
Patch33: Allow-gss_unwrap_iov-of-unpadded-RC4-tokens.patch
Patch34: Ignore-bad-enctypes-in-krb5_string_to_keysalts.patch
Patch35: Fix-leak-in-KERB_AP_OPTIONS_CBT-server-support.patch
Patch36: Fix-input-length-checking-in-SPNEGO-DER-decoding.patch
License: MIT
URL: https://web.mit.edu/kerberos/www/
@ -632,6 +633,9 @@ exit 0
%{_libdir}/libkadm5srv_mit.so.*
%changelog
* Wed Sep 09 2020 Robbie Harwood <rharwood@redhat.com> - 1.18.2-22
- Fix input length checking in SPNEGO DER decoding
* Fri Aug 28 2020 Robbie Harwood <rharwood@redhat.com> - 1.18.2-21
- Mark crypto-polices snippet as missingok
- Resolves: #1868379