AST-2022-005: pjproject - undefined behavior after freeing a dialog set

ASTERISK-29945 #close

Change-Id: Ia8ce6d82b115c82c1138747c72a0adcaa42b718c

third-party/pjproject/patches/0171-dialog-set-free.patch

+From db3235953baa56d2fb0e276ca510fefca751643f Mon Sep 17 00:00:00 2001
+From: Nanang Izzuddin <nanang@teluu.com>
+Date: Mon, 21 Feb 2022 06:24:52 +0700
+Subject: [PATCH] Merge pull request from GHSA-ffff-m5fm-qm62
+
+* Update pjsip_ua_unregister_dlg():
+- update the hash key if the dialog being unregistered is used as hash key.
+- add an assertion check to make sure that the dlg_set to be removed is valid (can be found in the hash table).
+
+* Change hash key string comparison method.
+---
+ pjsip/src/pjsip/sip_ua_layer.c | 48 +++++++++++++++++++++++++++++-----
+ 1 file changed, 42 insertions(+), 6 deletions(-)
+
+diff --git a/pjsip/src/pjsip/sip_ua_layer.c b/pjsip/src/pjsip/sip_ua_layer.c
+index 59c2524ba..5d79882a1 100644
+--- a/pjsip/src/pjsip/sip_ua_layer.c
++++ b/pjsip/src/pjsip/sip_ua_layer.c
+@@ -65,6 +65,9 @@ struct dlg_set
+     /* This is the buffer to store this entry in the hash table. */
+     pj_hash_entry_buf ht_entry;
+ 
++    /* Entry key in the hash table */
++    pj_str_t ht_key;
++
+     /* List of dialog in this dialog set. */
+     struct dlg_set_head  dlg_list;
+ };
+@@ -327,6 +330,7 @@ PJ_DEF(pj_status_t) pjsip_ua_register_dlg( pjsip_user_agent *ua,
+ 	     * Create the dialog set and add this dialog to it.
+ 	     */
+ 	    dlg_set = alloc_dlgset_node();
++	    dlg_set->ht_key = dlg->local.info->tag;
+ 	    pj_list_init(&dlg_set->dlg_list);
+ 	    pj_list_push_back(&dlg_set->dlg_list, dlg);
+ 
+@@ -334,8 +338,8 @@ PJ_DEF(pj_status_t) pjsip_ua_register_dlg( pjsip_user_agent *ua,
+ 
+ 	    /* Register the dialog set in the hash table. */
+ 	    pj_hash_set_np_lower(mod_ua.dlg_table, 
+-			         dlg->local.info->tag.ptr,
+-                                 (unsigned)dlg->local.info->tag.slen,
++			         dlg_set->ht_key.ptr,
++                                 (unsigned)dlg_set->ht_key.slen,
+ 			         dlg->local.tag_hval, dlg_set->ht_entry,
+                                  dlg_set);
+ 	}
+@@ -345,14 +349,15 @@ PJ_DEF(pj_status_t) pjsip_ua_register_dlg( pjsip_user_agent *ua,
+ 	struct dlg_set *dlg_set;
+ 
+ 	dlg_set = alloc_dlgset_node();
++	dlg_set->ht_key = dlg->local.info->tag;
+ 	pj_list_init(&dlg_set->dlg_list);
+ 	pj_list_push_back(&dlg_set->dlg_list, dlg);
+ 
+ 	dlg->dlg_set = dlg_set;
+ 
+ 	pj_hash_set_np_lower(mod_ua.dlg_table, 
+-		             dlg->local.info->tag.ptr,
+-                             (unsigned)dlg->local.info->tag.slen,
++		             dlg_set->ht_key.ptr,
++                             (unsigned)dlg_set->ht_key.slen,
+ 		             dlg->local.tag_hval, dlg_set->ht_entry, dlg_set);
+     }
+ 
+@@ -397,12 +402,43 @@ PJ_DEF(pj_status_t) pjsip_ua_unregister_dlg( pjsip_user_agent *ua,
+ 
+     /* If dialog list is empty, remove the dialog set from the hash table. */
+     if (pj_list_empty(&dlg_set->dlg_list)) {
+-	pj_hash_set_lower(NULL, mod_ua.dlg_table, dlg->local.info->tag.ptr,
+-		          (unsigned)dlg->local.info->tag.slen, 
++
++	/* Verify that the dialog set is valid */
++	pj_assert(pj_hash_get_lower(mod_ua.dlg_table, dlg_set->ht_key.ptr,
++				    (unsigned)dlg_set->ht_key.slen,
++				    &dlg->local.tag_hval) == dlg_set);
++
++	pj_hash_set_lower(NULL, mod_ua.dlg_table, dlg_set->ht_key.ptr,
++		          (unsigned)dlg_set->ht_key.slen,
+ 			  dlg->local.tag_hval, NULL);
+ 
+ 	/* Return dlg_set to free nodes. */
+ 	pj_list_push_back(&mod_ua.free_dlgset_nodes, dlg_set);
++    } else {
++	/* If the just unregistered dialog is being used as hash key,
++	 * reset the dlg_set entry with a new key (i.e: from the first dialog
++	 * in dlg_set).
++	 */
++	if (dlg_set->ht_key.ptr  == dlg->local.info->tag.ptr &&
++	    dlg_set->ht_key.slen == dlg->local.info->tag.slen)
++	{
++	    pjsip_dialog* key_dlg = dlg_set->dlg_list.next;
++
++	    /* Verify that the old & new keys share the hash value */
++	    pj_assert(key_dlg->local.tag_hval == dlg->local.tag_hval);
++
++	    pj_hash_set_lower(NULL, mod_ua.dlg_table, dlg_set->ht_key.ptr,
++			      (unsigned)dlg_set->ht_key.slen,
++			      dlg->local.tag_hval, NULL);
++
++	    dlg_set->ht_key = key_dlg->local.info->tag;
++
++	    pj_hash_set_np_lower(mod_ua.dlg_table,
++				 dlg_set->ht_key.ptr,
++				 (unsigned)dlg_set->ht_key.slen,
++				 key_dlg->local.tag_hval, dlg_set->ht_entry,
++				 dlg_set);
++	}
+     }
+ 
+     /* Unlock user agent. */
+-- 
+2.25.1
+