svn commit: r337031 - head/sys/security/mac
Mark Johnston
markj at FreeBSD.org
Wed Aug 1 03:46:08 UTC 2018
Author: markj
Date: Wed Aug 1 03:46:07 2018
New Revision: 337031
URL: https://svnweb.freebsd.org/changeset/base/337031
Log:
Require that MAC label buffers be able to store a non-empty string.
The buffer size may be used to initialize an sbuf in
MAC_POLICY_EXTERNALIZE, and without this constraint it's possible to
trigger an assertion failure in the sbuf code. With INVARIANTS
disabled, the first attempt to write to the sbuf will fail.
Reported by: pho
Reviewed by: delphij
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D16527
Modified:
head/sys/security/mac/mac_framework.c
Modified: head/sys/security/mac/mac_framework.c
==============================================================================
--- head/sys/security/mac/mac_framework.c Wed Aug 1 03:21:17 2018 (r337030)
+++ head/sys/security/mac/mac_framework.c Wed Aug 1 03:46:07 2018 (r337031)
@@ -586,7 +586,9 @@ int
mac_check_structmac_consistent(struct mac *mac)
{
- if (mac->m_buflen > MAC_MAX_LABEL_BUF_LEN)
+ /* Require that labels have a non-zero length. */
+ if (mac->m_buflen > MAC_MAX_LABEL_BUF_LEN ||
+ mac->m_buflen <= sizeof(""))
return (EINVAL);
return (0);
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