avahi: fix CVE-2023-38471

A vulnerability was found in Avahi. A reachable assertion exists
in the dbus_set_host_name function.

Signed-off-by: Meenali Gupta <meenali.gupta@windriver.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

2 files changed, 74 insertions, 0 deletions

diff --git a/meta/recipes-connectivity/avahi/avahi_0.8.bb b/meta/recipes-connectivity/avahi/avahi_0.8.bb
index a0b31a4697..9c903d6868 100644
--- a/meta/recipes-connectivity/avahi/avahi_0.8.bb
+++ b/meta/recipes-connectivity/avahi/avahi_0.8.bb
@@ -28,6 +28,7 @@ SRC_URI = "${GITHUB_BASE_URI}/download/v${PV}/avahi-${PV}.tar.gz \
            file://invalid-service.patch \
            file://CVE-2023-38469.patch \
            file://CVE-2023-38470.patch \
+           file://CVE-2023-38471.patch \
            "
 
 GITHUB_BASE_URI = "https://github.com/lathiat/avahi/releases/"
diff --git a/meta/recipes-connectivity/avahi/files/CVE-2023-38471.patch b/meta/recipes-connectivity/avahi/files/CVE-2023-38471.patch
new file mode 100644
index 0000000000..b3f716495d
--- /dev/null
+++ b/meta/recipes-connectivity/avahi/files/CVE-2023-38471.patch
@@ -0,0 +1,73 @@
+From 48d745db7fd554fc33e96ec86d3675ebd530bb8e Mon Sep 17 00:00:00 2001
+From: Michal Sekletar <msekleta@redhat.com>
+Date: Mon, 23 Oct 2023 13:38:35 +0200
+Subject: [PATCH] avahi: core: extract host name using avahi_unescape_label()
+
+Previously we could create invalid escape sequence when we split the
+string on dot. For example, from valid host name "foo\\.bar" we have
+created invalid name "foo\\" and tried to set that as the host name
+which crashed the daemon.
+
+Fixes #453
+
+Upstream-Status: Backport [https://github.com/lathiat/avahi/commit/894f085f402e023a98cbb6f5a3d117bd88d93b09]
+CVE: CVE-2023-38471
+
+Signed-off-by: Meenali Gupta <meenali.gupta@windriver.com>
+---
+ avahi-core/server.c | 27 +++++++++++++++++++++------
+ 1 file changed, 21 insertions(+), 6 deletions(-)
+
+diff --git a/avahi-core/server.c b/avahi-core/server.c
+index e507750..40f1d68 100644
+--- a/avahi-core/server.c
++++ b/avahi-core/server.c
+@@ -1295,7 +1295,11 @@ static void update_fqdn(AvahiServer *s) {
+ }
+
+ int avahi_server_set_host_name(AvahiServer *s, const char *host_name) {
+-    char *hn = NULL;
++    char label_escaped[AVAHI_LABEL_MAX*4+1];
++    char label[AVAHI_LABEL_MAX];
++    char *hn = NULL, *h;
++    size_t len;
++
+     assert(s);
+
+     AVAHI_CHECK_VALIDITY(s, !host_name || avahi_is_valid_host_name(host_name), AVAHI_ERR_INVALID_HOST_NAME);
+@@ -1305,17 +1309,28 @@ int avahi_server_set_host_name(AvahiServer *s, const char *host_name) {
+     else
+         hn = avahi_normalize_name_strdup(host_name);
+
+-    hn[strcspn(hn, ".")] = 0;
++    h = hn;
++    if (!avahi_unescape_label((const char **)&hn, label, sizeof(label))) {
++        avahi_free(h);
++        return AVAHI_ERR_INVALID_HOST_NAME;
++    }
++
++    avahi_free(h);
++
++    h = label_escaped;
++    len = sizeof(label_escaped);
++    if (!avahi_escape_label(label, strlen(label), &h, &len))
++        return AVAHI_ERR_INVALID_HOST_NAME;
+
+-    if (avahi_domain_equal(s->host_name, hn) && s->state != AVAHI_SERVER_COLLISION) {
+-        avahi_free(hn);
++    if (avahi_domain_equal(s->host_name, label_escaped) && s->state != AVAHI_SERVER_COLLISION)
+         return avahi_server_set_errno(s, AVAHI_ERR_NO_CHANGE);
+-    }
+
+     withdraw_host_rrs(s);
+
+     avahi_free(s->host_name);
+-    s->host_name = hn;
++    s->host_name = avahi_strdup(label_escaped);
++    if (!s->host_name)
++        return AVAHI_ERR_NO_MEMORY;
+
+     update_fqdn(s);
+
+--
+2.40.0