CVE: CVE-2021-36217
Upstream-Status: Backport
Signed-off-by: Ross Burton <ross.burton@arm.com>

From 9d31939e55280a733d930b15ac9e4dda4497680c Mon Sep 17 00:00:00 2001
From: Tommi Rantala <tommi.t.rantala@nokia.com>
Date: Mon, 8 Feb 2021 11:04:43 +0200
Subject: [PATCH] Fix NULL pointer crashes from #175

avahi-daemon is crashing when running "ping .local".
The crash is due to failing assertion from NULL pointer.
Add missing NULL pointer checks to fix it.

Introduced in #175 - merge commit 8f75a045709a780c8cf92a6a21e9d35b593bdecd
---
 avahi-core/browse-dns-server.c   | 5 ++++-
 avahi-core/browse-domain.c       | 5 ++++-
 avahi-core/browse-service-type.c | 3 +++
 avahi-core/browse-service.c      | 3 +++
 avahi-core/browse.c              | 3 +++
 avahi-core/resolve-address.c     | 5 ++++-
 avahi-core/resolve-host-name.c   | 5 ++++-
 avahi-core/resolve-service.c     | 5 ++++-
 8 files changed, 29 insertions(+), 5 deletions(-)

diff --git a/avahi-core/browse-dns-server.c b/avahi-core/browse-dns-server.c
index 049752e9..c2d914fa 100644
--- a/avahi-core/browse-dns-server.c
+++ b/avahi-core/browse-dns-server.c
@@ -343,7 +343,10 @@ AvahiSDNSServerBrowser *avahi_s_dns_server_browser_new(
         AvahiSDNSServerBrowser* b;
 
         b = avahi_s_dns_server_browser_prepare(server, interface, protocol, domain, type, aprotocol, flags, callback, userdata);
+        if (!b)
+            return NULL;
+
         avahi_s_dns_server_browser_start(b);
 
         return b;
-}
\ No newline at end of file
+}
diff --git a/avahi-core/browse-domain.c b/avahi-core/browse-domain.c
index f145d56a..06fa70c0 100644
--- a/avahi-core/browse-domain.c
+++ b/avahi-core/browse-domain.c
@@ -253,7 +253,10 @@ AvahiSDomainBrowser *avahi_s_domain_browser_new(
         AvahiSDomainBrowser *b;
 
         b = avahi_s_domain_browser_prepare(server, interface, protocol, domain, type, flags, callback, userdata);
+        if (!b)
+            return NULL;
+
         avahi_s_domain_browser_start(b);
 
         return b;
-}
\ No newline at end of file
+}
diff --git a/avahi-core/browse-service-type.c b/avahi-core/browse-service-type.c
index fdd22dcd..b1fc7af8 100644
--- a/avahi-core/browse-service-type.c
+++ b/avahi-core/browse-service-type.c
@@ -171,6 +171,9 @@ AvahiSServiceTypeBrowser *avahi_s_service_type_browser_new(
         AvahiSServiceTypeBrowser *b;
 
         b = avahi_s_service_type_browser_prepare(server, interface, protocol, domain, flags, callback, userdata);
+        if (!b)
+            return NULL;
+
         avahi_s_service_type_browser_start(b);
 
         return b;
diff --git a/avahi-core/browse-service.c b/avahi-core/browse-service.c
index 5531360c..63e0275a 100644
--- a/avahi-core/browse-service.c
+++ b/avahi-core/browse-service.c
@@ -184,6 +184,9 @@ AvahiSServiceBrowser *avahi_s_service_browser_new(
         AvahiSServiceBrowser *b;
 
         b = avahi_s_service_browser_prepare(server, interface, protocol, service_type, domain, flags, callback, userdata);
+        if (!b)
+            return NULL;
+
         avahi_s_service_browser_start(b);
 
         return b;
diff --git a/avahi-core/browse.c b/avahi-core/browse.c
index 2941e579..e8a915e9 100644
--- a/avahi-core/browse.c
+++ b/avahi-core/browse.c
@@ -634,6 +634,9 @@ AvahiSRecordBrowser *avahi_s_record_browser_new(
         AvahiSRecordBrowser *b;
 
         b = avahi_s_record_browser_prepare(server, interface, protocol, key, flags, callback, userdata);
+        if (!b)
+            return NULL;
+
         avahi_s_record_browser_start_query(b);
 
         return b;
diff --git a/avahi-core/resolve-address.c b/avahi-core/resolve-address.c
index ac0b29b1..e61dd242 100644
--- a/avahi-core/resolve-address.c
+++ b/avahi-core/resolve-address.c
@@ -286,7 +286,10 @@ AvahiSAddressResolver *avahi_s_address_resolver_new(
         AvahiSAddressResolver *b;
 
         b = avahi_s_address_resolver_prepare(server, interface, protocol, address, flags, callback, userdata);
+        if (!b)
+            return NULL;
+
         avahi_s_address_resolver_start(b);
 
         return b;
-}
\ No newline at end of file
+}
diff --git a/avahi-core/resolve-host-name.c b/avahi-core/resolve-host-name.c
index 808b0e72..4e8e5973 100644
--- a/avahi-core/resolve-host-name.c
+++ b/avahi-core/resolve-host-name.c
@@ -318,7 +318,10 @@ AvahiSHostNameResolver *avahi_s_host_name_resolver_new(
         AvahiSHostNameResolver *b;
 
         b = avahi_s_host_name_resolver_prepare(server, interface, protocol, host_name, aprotocol, flags, callback, userdata);
+        if (!b)
+            return NULL;
+
         avahi_s_host_name_resolver_start(b);
 
         return b;
-}
\ No newline at end of file
+}
diff --git a/avahi-core/resolve-service.c b/avahi-core/resolve-service.c
index 66bf3cae..43771763 100644
--- a/avahi-core/resolve-service.c
+++ b/avahi-core/resolve-service.c
@@ -519,7 +519,10 @@ AvahiSServiceResolver *avahi_s_service_resolver_new(
         AvahiSServiceResolver *b;
 
         b = avahi_s_service_resolver_prepare(server, interface, protocol, name, type, domain, aprotocol, flags, callback, userdata);
+        if (!b)
+            return NULL;
+
         avahi_s_service_resolver_start(b);
 
         return b;
-}
\ No newline at end of file
+}