AST-2012-011: Resolve heap corruption issue with voicemail

The heard and deleted arrays in the voicemail state structure were not
handled properly following the memory leak fix in r354890 and a fix for
an invalid free in r356797.  This could result in accessing and writing
into freed memory.  The allocation for these arrays has been reworked
to avoid the possibility of invalid frees, access of freed memory, and
crashes that were occurring as a result of this.

Locking around accesses and modifications of the voicemail state
structure members dh_arraysize, heard, and deleted has been added to
prevent simultaneous modification and access when IMAP storage is in
use.  If IMAP storage is not in use, this locking is not compiled in.

Review: https://reviewboard.asterisk.org/r/1994/
(closes issue ASTERISK-19923)
Reported by: Dan Delaney
Tested by: Dan Delaney, Julian Yap
Patches:
  vm_alloc_fix.diff uploaded by kmoore (license 6273)

........

Merged revisions 369652 from http://svn.asterisk.org/svn/asterisk/branches/1.8
........

Merged revisions 369653 from http://svn.asterisk.org/svn/asterisk/branches/10


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@369676 65c4cc65-6c06-0410-ace0-fbb531ad65f3

apps/app_voicemail.c

@@ -1915,25 +1915,28 @@ static void free_user(struct ast_vm_user *vmu)
 static int vm_allocate_dh(struct vm_state *vms, struct ast_vm_user *vmu, int count_msg) {
 
 	int arraysize = (vmu->maxmsg > count_msg ? vmu->maxmsg : count_msg);
-	if (!vms->dh_arraysize) {
+
-		/* initial allocation */
+	/* remove old allocation */
+	if (vms->deleted) {
+		ast_free(vms->deleted);
+		vms->deleted = NULL;
+	}
+	if (vms->heard) {
+		ast_free(vms->heard);
+		vms->heard = NULL;
+	}
+	vms->dh_arraysize = 0;
+
+	if (arraysize > 0) {
 		if (!(vms->deleted = ast_calloc(arraysize, sizeof(int)))) {
 			return -1;
 		}
 		if (!(vms->heard = ast_calloc(arraysize, sizeof(int)))) {
+			ast_free(vms->deleted);
+			vms->deleted = NULL;
 			return -1;
 		}
 		vms->dh_arraysize = arraysize;
-	} else if (vms->dh_arraysize < arraysize) {
-		if (!(vms->deleted = ast_realloc(vms->deleted, arraysize * sizeof(int)))) {
-			return -1;
-		}
-		if (!(vms->heard = ast_realloc(vms->heard, arraysize * sizeof(int)))) {
-			return -1;
-		}
-		memset(vms->deleted, 0, arraysize * sizeof(int));
-		memset(vms->heard, 0, arraysize * sizeof(int));
-		vms->dh_arraysize = arraysize;
 	}
 
 	return 0;
@@ -7192,13 +7195,20 @@ static void adsi_message(struct ast_channel *chan, struct vm_state *vms)
 		ast_callerid_parse(cid, &name, &num);
 		if (!name)
 			name = num;
-	} else
+	} else {
 		name = "Unknown Caller";
+	}
 
 	/* If deleted, show "undeleted" */
-
+#ifdef IMAP_STORAGE
-	if (vms->deleted[vms->curmsg])
+	ast_mutex_lock(&vms->lock);
+#endif
+	if (vms->deleted[vms->curmsg]) {
 		keys[1] = ADSI_KEY_SKT | (ADSI_KEY_APPS + 11);
+	}
+#ifdef IMAP_STORAGE
+	ast_mutex_unlock(&vms->lock);
+#endif
 
 	/* Except "Exit" */
 	keys[5] = ADSI_KEY_SKT | (ADSI_KEY_APPS + 5);
@@ -7251,8 +7261,15 @@ static void adsi_delete(struct ast_channel *chan, struct vm_state *vms)
 	}
 
 	/* If deleted, show "undeleted" */
-	if (vms->deleted[vms->curmsg]) 
+#ifdef IMAP_STORAGE
+	ast_mutex_lock(&vms->lock);
+#endif
+	if (vms->deleted[vms->curmsg]) {
 		keys[1] = ADSI_KEY_SKT | (ADSI_KEY_APPS + 11);
+	}
+#ifdef IMAP_STORAGE
+	ast_mutex_unlock(&vms->lock);
+#endif
 
 	/* Except "Exit" */
 	keys[5] = ADSI_KEY_SKT | (ADSI_KEY_APPS + 5);
@@ -8503,8 +8520,12 @@ static int play_message(struct ast_channel *chan, struct ast_vm_user *vmu, struc
 
 	if (!res) {
 		make_file(vms->fn, sizeof(vms->fn), vms->curdir, vms->curmsg);
+#ifdef IMAP_STORAGE
+		ast_mutex_lock(&vms->lock);
+#endif
 		vms->heard[vms->curmsg] = 1;
 #ifdef IMAP_STORAGE
+		ast_mutex_unlock(&vms->lock);
 		/*IMAP storage stores any prepended message from a forward
 		 * as a separate file from the rest of the message
 		 */
@@ -8719,6 +8740,7 @@ static int close_mailbox(struct vm_state *vms, struct ast_vm_user *vmu)
 	}
 	ast_unlock_path(vms->curdir);
 #else /* defined(IMAP_STORAGE) */
+	ast_mutex_lock(&vms->lock);
 	if (vms->deleted) {
 		/* Since we now expunge after each delete, deleting in reverse order
 		 * ensures that no reordering occurs between each step. */
@@ -8733,12 +8755,18 @@ static int close_mailbox(struct vm_state *vms, struct ast_vm_user *vmu)
 #endif
 
 done:
-	if (vms->deleted && last_msg_idx) {
+	if (vms->deleted) {
 		ast_free(vms->deleted);
+		vms->deleted = NULL;
 	}
-	if (vms->heard && last_msg_idx) {
+	if (vms->heard) {
 		ast_free(vms->heard);
+		vms->heard = NULL;
 	}
+	vms->dh_arraysize = 0;
+#ifdef IMAP_STORAGE
+	ast_mutex_unlock(&vms->lock);
+#endif
 
 	return 0;
 }
@@ -9833,14 +9861,25 @@ static int vm_instructions_en(struct ast_channel *chan, struct ast_vm_user *vmu,
 				res = ast_play_and_wait(chan, "vm-next");
 			}
 			if (!res) {
-				if (!vms->deleted[vms->curmsg])
+				int curmsg_deleted;
+#ifdef IMAP_STORAGE
+				ast_mutex_lock(&vms->lock);
+#endif
+				curmsg_deleted = vms->deleted[vms->curmsg];
+#ifdef IMAP_STORAGE
+				ast_mutex_unlock(&vms->lock);
+#endif
+				if (!curmsg_deleted) {
 					res = ast_play_and_wait(chan, "vm-delete");
-				else
+				} else {
 					res = ast_play_and_wait(chan, "vm-undelete");
-				if (!res)
+				}
+				if (!res) {
 					res = ast_play_and_wait(chan, "vm-toforward");
-				if (!res)
+				}
+				if (!res) {
 					res = ast_play_and_wait(chan, "vm-savemessage");
+				}
 			}
 		}
 		if (!res) {
@@ -10591,7 +10630,13 @@ static int play_message_by_id_helper(struct ast_channel *chan,
 	if ((wait_file(chan, vms, vms->fn)) < 0) {
 		ast_log(AST_LOG_WARNING, "Playback of message %s failed\n", vms->fn);
 	} else {
+#ifdef IMAP_STORAGE
+		ast_mutex_lock(&vms->lock);
+#endif
 		vms->heard[vms->curmsg] = 1;
+#ifdef IMAP_STORAGE
+		ast_mutex_unlock(&vms->lock);
+#endif
 	}
 
 	return 0;
@@ -11012,6 +11057,7 @@ static int vm_execmain(struct ast_channel *chan, const char *data)
 			}
 
 			vms.starting = 1;
+			vms.curmsg = 0;
 			break;
 		case '3': /* Advanced options */
 			ast_test_suite_event_notify("ADVOPTIONS", "Message: entering advanced options menu");