avahi: fix CVE-2023-38473

A vulnerability was found in Avahi. A reachable assertion exists
in the avahi_alternative_host_name() function.

(From OE-Core rev: fbe506e7af1ce47f6d04c122cb77573e0527ab91)

Signed-off-by: Meenali Gupta <meenali.gupta@windriver.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

2 files changed, 111 insertions, 0 deletions

diff --git a/meta/recipes-connectivity/avahi/avahi_0.8.bb b/meta/recipes-connectivity/avahi/avahi_0.8.bb
index 84eb1c554d..910da3c9cc 100644
--- a/meta/recipes-connectivity/avahi/avahi_0.8.bb
+++ b/meta/recipes-connectivity/avahi/avahi_0.8.bb
@@ -30,6 +30,7 @@ SRC_URI = "${GITHUB_BASE_URI}/download/v${PV}/avahi-${PV}.tar.gz \
            file://CVE-2023-38470.patch \
            file://CVE-2023-38471.patch \
            file://CVE-2023-38472.patch \
+           file://CVE-2023-38473.patch \
            "
 
 GITHUB_BASE_URI = "https://github.com/lathiat/avahi/releases/"
diff --git a/meta/recipes-connectivity/avahi/files/CVE-2023-38473.patch b/meta/recipes-connectivity/avahi/files/CVE-2023-38473.patch
new file mode 100644
index 0000000000..707acb60fe
--- /dev/null
+++ b/meta/recipes-connectivity/avahi/files/CVE-2023-38473.patch
@@ -0,0 +1,110 @@
+From 88cbbc48d5efff9726694557ca6c3f698f3affe4 Mon Sep 17 00:00:00 2001
+From: Michal Sekletar <msekleta@redhat.com>
+Date: Wed, 11 Oct 2023 17:45:44 +0200
+Subject: [PATCH] avahi: 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
+
+Upstream-Status: Backport [https://github.com/lathiat/avahi/commit/b448c9f771bada14ae8de175695a9729f8646797]
+CVE: CVE-2023-38473
+
+Signed-off-by: Meenali Gupta <meenali.gupta@windriver.com>
+---
+ 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;
+--
+2.40.0