Bug#993276: bullseye-pu: package krb5/1.18.3-6+deb11u1
Package: release.debian.org
Severity: normal
Tags: bullseye
User: release.debian.org@packages.debian.org
Usertags: pu
[ Reason ]
Fixing one no-DSA security advisory an an memory leak that was actually bothering a user enough to get tracked down.
I've confirmed that package passes autopkgtest on bullseye.
[ Impact ]
Authenticated attackers can crash a KDC and if they do it fast enough it won't auto-restart.
A memory leak will persist.
[ Tests ]
Upstream has introduced tests to confirm the fixes.
The changes are very small and targeted.
[ Risks ]
Small changes easily reviewed.
[ Checklist ]
[x] *all* changes are documented in the d/changelog
[x] I reviewed all changes and I approve them
[x] attach debdiff against the package in (old)stable
[ ] the issue is verified as fixed in unstable
[ Changes ]
diff --git a/debian/changelog b/debian/changelog
index f4beefd80c..0be31136f4 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,12 @@
+krb5 (1.18.3-6+deb11u1) bullseye; urgency=medium
+
+ * Fix KDC null dereference crash on FAST request with no server field,
+ CVE-2021-37750, Closes: #992607
+ * Fix memory leak in krb5_gss_inquire_cred, Closes: #991140
+
+
+ -- Sam Hartman <hartmans@debian.org> Sun, 29 Aug 2021 16:38:12 -0600
+
krb5 (1.18.3-6) unstable; urgency=high
* Pull in upstream patch to fix CVE-2021-36222 (KDC NULL dereference),
diff --git a/debian/patches/0011-Fix-KDC-null-deref-on-TGS-inner-body-null-server.patch b/debian/patches/0011-Fix-KDC-null-deref-on-TGS-inner-body-null-server.patch
new file mode 100644
index 0000000000..970a80cc89
--- /dev/null
+++ b/debian/patches/0011-Fix-KDC-null-deref-on-TGS-inner-body-null-server.patch
@@ -0,0 +1,44 @@
+From: Greg Hudson <ghudson@mit.edu>
+Date: Tue, 3 Aug 2021 01:15:27 -0400
+Subject: Fix KDC null deref on TGS inner body null server
+
+After the KDC decodes a FAST inner body, it does not check for a null
+server. Prior to commit 39548a5b17bbda9eeb63625a201cfd19b9de1c5b this
+would typically result in an error from krb5_unparse_name(), but with
+the addition of get_local_tgt() it results in a null dereference. Add
+a null check.
+
+Reported by Joseph Sutton of Catalyst.
+
+CVE-2021-37750:
+
+In MIT krb5 releases 1.14 and later, an authenticated attacker can
+cause a null dereference in the KDC by sending a FAST TGS request with
+no server field.
+
+ticket: 9008 (new)
+tags: pullup
+target_version: 1.19-next
+target_version: 1.18-next
+
+(cherry picked from commit d775c95af7606a51bf79547a94fa52ddd1cb7f49)
+---
+ src/kdc/do_tgs_req.c | 5 +++++
+ 1 file changed, 5 insertions(+)
+
+diff --git a/src/kdc/do_tgs_req.c b/src/kdc/do_tgs_req.c
+index 241f34e..386ed5f 100644
+--- a/src/kdc/do_tgs_req.c
++++ b/src/kdc/do_tgs_req.c
+@@ -208,6 +208,11 @@ process_tgs_req(krb5_kdc_req *request, krb5_data *pkt,
+ status = "FIND_FAST";
+ goto cleanup;
+ }
++ if (sprinc == NULL) {
++ status = "NULL_SERVER";
++ errcode = KRB5KDC_ERR_S_PRINCIPAL_UNKNOWN;
++ goto cleanup;
++ }
+
+ errcode = get_local_tgt(kdc_context, &sprinc->realm, header_server,
+ &local_tgt, &local_tgt_storage, &local_tgt_key);
diff --git a/debian/patches/0012-Fix-defcred-leak-in-krb5-gss_inquire_cred.patch b/debian/patches/0012-Fix-defcred-leak-in-krb5-gss_inquire_cred.patch
new file mode 100644
index 0000000000..3c81bf0666
--- /dev/null
+++ b/debian/patches/0012-Fix-defcred-leak-in-krb5-gss_inquire_cred.patch
@@ -0,0 +1,41 @@
+From: Greg Hudson <ghudson@mit.edu>
+Date: Wed, 21 Jul 2021 13:44:30 -0400
+Subject: Fix defcred leak in krb5 gss_inquire_cred()
+MIME-Version: 1.0
+Content-Type: text/plain; charset="utf-8"
+Content-Transfer-Encoding: 8bit
+
+Commit 1cd2821c19b2b95e39d5fc2f451a035585a40fa5 altered the memory
+management of krb5_gss_inquire_cred(), introducing defcred to act as
+an owner pointer when the function must acquire a default credential.
+The commit neglected to update the code to release the default cred
+along the successful path. The old code does not trigger because
+cred_handle is now reassigned, so the default credential is leaked.
+
+Reported by Pavel Březina.
+
+(a minimal alternative to commit 593e16448e1af23eef74689afe06a7bcc86e79c7)
+
+ticket: 9016
+version_fixed: 1.18.4
+
+(cherry picked from commit b92be484630b38e26f5ee4bd67973fbd7627009c)
+---
+ src/lib/gssapi/krb5/inq_cred.c | 4 +---
+ 1 file changed, 1 insertion(+), 3 deletions(-)
+
+diff --git a/src/lib/gssapi/krb5/inq_cred.c b/src/lib/gssapi/krb5/inq_cred.c
+index a8f2541..cd8384d 100644
+--- a/src/lib/gssapi/krb5/inq_cred.c
++++ b/src/lib/gssapi/krb5/inq_cred.c
+@@ -197,9 +197,7 @@ krb5_gss_inquire_cred(minor_status, cred_handle, name, lifetime_ret,
+ mechs = GSS_C_NO_OID_SET;
+ }
+
+- if (cred_handle == GSS_C_NO_CREDENTIAL)
+- krb5_gss_release_cred(minor_status, (gss_cred_id_t *)&cred);
+-
++ krb5_gss_release_cred(minor_status, &defcred);
+ krb5_free_context(context);
+ *minor_status = 0;
+ return((lifetime == 0)?GSS_S_CREDENTIALS_EXPIRED:GSS_S_COMPLETE);
diff --git a/debian/patches/series b/debian/patches/series
index 0478b278b0..23f41f56da 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -8,3 +8,5 @@ debian-local/0007-Fix-pkg-config-library-include-paths.patch
debian-local/0008-Use-isystem-for-include-paths.patch
0009-Add-.gitignore.patch
0010-Fix-KDC-null-deref-on-bad-encrypted-challenge.patch
+0011-Fix-KDC-null-deref-on-TGS-inner-body-null-server.patch
+0012-Fix-defcred-leak-in-krb5-gss_inquire_cred.patch
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