Author: rmacklem
Date: Wed May 1 22:07:55 2013
New Revision: 250157
URL: http://svnweb.freebsd.org/changeset/base/250157
Log:
Isilon reported that sec=krb5p NFS mounts had a problem when m_len == 0
for the last mbuf of the list with an encrypted message. This patch replaces
the KASSERT() with code that handles this case.
Reported by: john.gemign...@isilon.com
Reviewed by: jhb
MFC after: 2 weeks
Modified:
head/sys/kgssapi/krb5/krb5_mech.c
Modified: head/sys/kgssapi/krb5/krb5_mech.c
==============================================================================
--- head/sys/kgssapi/krb5/krb5_mech.c Wed May 1 21:53:38 2013
(r250156)
+++ head/sys/kgssapi/krb5/krb5_mech.c Wed May 1 22:07:55 2013
(r250157)
@@ -1585,6 +1585,8 @@ m_trim(struct mbuf *m, int len)
struct mbuf *n;
int off;
+ if (m == NULL)
+ return;
n = m_getptr(m, len, &off);
if (n) {
n->m_len = off;
@@ -1600,7 +1602,7 @@ krb5_unwrap_old(struct krb5_context *kc,
uint8_t sgn_alg[2], uint8_t seal_alg[2])
{
OM_uint32 res;
- struct mbuf *m, *mlast, *hm, *cm;
+ struct mbuf *m, *mlast, *hm, *cm, *n;
uint8_t *p, dir;
size_t mlen, tlen, elen, datalen, padlen;
size_t cklen;
@@ -1702,9 +1704,25 @@ krb5_unwrap_old(struct krb5_context *kc,
/*
* Check the trailing pad bytes.
+ * RFC1964 specifies between 1<->8 bytes, each with a binary value
+ * equal to the number of bytes.
*/
- KASSERT(mlast->m_len > 0, ("Unexpected empty mbuf"));
- padlen = mlast->m_data[mlast->m_len - 1];
+ if (mlast->m_len > 0)
+ padlen = mlast->m_data[mlast->m_len - 1];
+ else {
+ n = m_getptr(m, tlen + datalen - 1, &i);
+ /*
+ * When the position is exactly equal to the # of data bytes
+ * in the mbuf list, m_getptr() will return the last mbuf in
+ * the list and an off == m_len for that mbuf, so that case
+ * needs to be checked as well as a NULL return.
+ */
+ if (n == NULL || n->m_len == i)
+ return (GSS_S_DEFECTIVE_TOKEN);
+ padlen = n->m_data[i];
+ }
+ if (padlen < 1 || padlen > 8 || padlen > tlen + datalen)
+ return (GSS_S_DEFECTIVE_TOKEN);
m_copydata(m, tlen + datalen - padlen, padlen, buf);
for (i = 0; i < padlen; i++) {
if (buf[i] != padlen) {
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