Fix CVE-2023-38473

Resolves: RHEL-5643

0001-common-derive-alternative-host-name-from-its-unescap.patch

@@ -0,0 +1,107 @@
+From b448c9f771bada14ae8de175695a9729f8646797 Mon Sep 17 00:00:00 2001
+From: Michal Sekletar <msekleta@redhat.com>
+Date: Wed, 11 Oct 2023 17:45:44 +0200
+Subject: [PATCH] common: derive alternative host name from its unescaped
+ version
+
+Normalization of input makes sure we don't have to deal with special
+cases like unescaped dot at the end of label.
+
+Fixes #451 #487
+CVE-2023-38473
+---
+ avahi-common/alternative-test.c |  3 +++
+ avahi-common/alternative.c      | 27 +++++++++++++++++++--------
+ 2 files changed, 22 insertions(+), 8 deletions(-)
+
+diff --git a/avahi-common/alternative-test.c b/avahi-common/alternative-test.c
+index 9255435..681fc15 100644
+--- a/avahi-common/alternative-test.c
++++ b/avahi-common/alternative-test.c
+@@ -31,6 +31,9 @@ int main(AVAHI_GCC_UNUSED int argc, AVAHI_GCC_UNUSED char *argv[]) {
+     const char* const test_strings[] = {
+         "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX",
+         "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXüüüüüüü",
++        ").",
++        "\\.",
++        "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA\\\\",
+         "gurke",
+         "-",
+         " #",
+diff --git a/avahi-common/alternative.c b/avahi-common/alternative.c
+index b3d39f0..a094e6d 100644
+--- a/avahi-common/alternative.c
++++ b/avahi-common/alternative.c
+@@ -49,15 +49,20 @@ static void drop_incomplete_utf8(char *c) {
+ }
+ 
+ char *avahi_alternative_host_name(const char *s) {
++    char label[AVAHI_LABEL_MAX], alternative[AVAHI_LABEL_MAX*4+1];
++    char *alt, *r, *ret;
+     const char *e;
+-    char *r;
++    size_t len;
+ 
+     assert(s);
+ 
+     if (!avahi_is_valid_host_name(s))
+         return NULL;
+ 
+-    if ((e = strrchr(s, '-'))) {
++    if (!avahi_unescape_label(&s, label, sizeof(label)))
++        return NULL;
++
++    if ((e = strrchr(label, '-'))) {
+         const char *p;
+ 
+         e++;
+@@ -74,19 +79,18 @@ char *avahi_alternative_host_name(const char *s) {
+ 
+     if (e) {
+         char *c, *m;
+-        size_t l;
+         int n;
+ 
+         n = atoi(e)+1;
+         if (!(m = avahi_strdup_printf("%i", n)))
+             return NULL;
+ 
+-        l = e-s-1;
++        len = e-label-1;
+ 
+-        if (l >= AVAHI_LABEL_MAX-1-strlen(m)-1)
+-            l = AVAHI_LABEL_MAX-1-strlen(m)-1;
++        if (len >= AVAHI_LABEL_MAX-1-strlen(m)-1)
++            len = AVAHI_LABEL_MAX-1-strlen(m)-1;
+ 
+-        if (!(c = avahi_strndup(s, l))) {
++        if (!(c = avahi_strndup(label, len))) {
+             avahi_free(m);
+             return NULL;
+         }
+@@ -100,7 +104,7 @@ char *avahi_alternative_host_name(const char *s) {
+     } else {
+         char *c;
+ 
+-        if (!(c = avahi_strndup(s, AVAHI_LABEL_MAX-1-2)))
++        if (!(c = avahi_strndup(label, AVAHI_LABEL_MAX-1-2)))
+             return NULL;
+ 
+         drop_incomplete_utf8(c);
+@@ -109,6 +113,13 @@ char *avahi_alternative_host_name(const char *s) {
+         avahi_free(c);
+     }
+ 
++    alt = alternative;
++    len = sizeof(alternative);
++    ret = avahi_escape_label(r, strlen(r), &alt, &len);
++
++    avahi_free(r);
++    r = avahi_strdup(ret);
++
+     assert(avahi_is_valid_host_name(r));
+ 
+     return r;
+-- 
+2.41.0
+

avahi.spec

@@ -26,7 +26,7 @@
 
 Name:             avahi
 Version:          0.7
-Release:          23%{?dist}
+Release:          24%{?dist}
 Summary:          Local network service discovery
 License:          LGPLv2+
 URL:              http://avahi.org
@@ -91,6 +91,7 @@ Patch0006:  0001-Emit-error-if-requested-service-is-not-found.patch
 Patch0007:  0001-Ensure-each-label-is-at-least-one-byte-long.patch
 Patch0008:  0001-core-make-sure-there-is-rdata-to-process-before-pars.patch
 Patch0009:  0001-core-copy-resource-records-with-zero-length-rdata-pr.patch
+Patch0010:  0001-common-derive-alternative-host-name-from-its-unescap.patch
 
 ## downstream patches
 Patch100:         avahi-0.6.30-mono-libdir.patch
@@ -659,6 +660,9 @@ exit 0
 
 
 %changelog
+* Thu Nov 09 2023 Michal Sekletar <msekleta@redhat.com> - 0.7-24
+- Fix CVE-2023-38473 (RHEL-5643)
+
 * Thu Nov 09 2023 Michal Sekletar <msekleta@redhat.com> - 0.7-23
 - Fix CVE-2023-38472 (RHEL-5644)