[29107] in CVS-changelog-for-Kerberos-V5
krb5 commit: Fix build_principal memory bug [CVE-2015-2697]
daemon@ATHENA.MIT.EDU (Greg Hudson)
Mon Oct 26 13:44:54 2015
Date: Mon, 26 Oct 2015 13:44:50 -0400
From: Greg Hudson <ghudson@mit.edu>
Message-Id: <201510261744.t9QHioVa017323@drugstore.mit.edu>
To: cvs-krb5@mit.edu
Reply-To: krbdev@mit.edu
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Errors-To: cvs-krb5-bounces@mit.edu
https://github.com/krb5/krb5/commit/f0c094a1b745d91ef2f9a4eae2149aac026a5789
commit f0c094a1b745d91ef2f9a4eae2149aac026a5789
Author: Greg Hudson <ghudson@mit.edu>
Date: Fri Sep 25 12:51:47 2015 -0400
Fix build_principal memory bug [CVE-2015-2697]
In build_principal_va(), use k5memdup0() instead of strdup() to make a
copy of the realm, to ensure that we allocate the correct number of
bytes and do not read past the end of the input string. This bug
affects krb5_build_principal(), krb5_build_principal_va(), and
krb5_build_principal_alloc_va(). krb5_build_principal_ext() is not
affected.
CVE-2015-2697:
In MIT krb5 1.7 and later, an authenticated attacker may be able to
cause a KDC to crash using a TGS request with a large realm field
beginning with a null byte. If the KDC attempts to find a referral to
answer the request, it constructs a principal name for lookup using
krb5_build_principal() with the requested realm. Due to a bug in this
function, the null byte causes only one byte be allocated for the
realm field of the constructed principal, far less than its length.
Subsequent operations on the lookup principal may cause a read beyond
the end of the mapped memory region, causing the KDC process to crash.
CVSSv2: AV:N/AC:L/Au:S/C:N/I:N/A:C/E:POC/RL:OF/RC:C
ticket: 8252 (new)
target_version: 1.14
tags: pullup
src/lib/krb5/krb/bld_princ.c | 6 ++----
1 files changed, 2 insertions(+), 4 deletions(-)
diff --git a/src/lib/krb5/krb/bld_princ.c b/src/lib/krb5/krb/bld_princ.c
index ab6fed8..8604268 100644
--- a/src/lib/krb5/krb/bld_princ.c
+++ b/src/lib/krb5/krb/bld_princ.c
@@ -40,10 +40,8 @@ build_principal_va(krb5_context context, krb5_principal princ,
data = malloc(size * sizeof(krb5_data));
if (!data) { retval = ENOMEM; }
- if (!retval) {
- r = strdup(realm);
- if (!r) { retval = ENOMEM; }
- }
+ if (!retval)
+ r = k5memdup0(realm, rlen, &retval);
while (!retval && (component = va_arg(ap, char *))) {
if (count == size) {
_______________________________________________
cvs-krb5 mailing list
cvs-krb5@mit.edu
https://mailman.mit.edu/mailman/listinfo/cvs-krb5
