From 056c9137cc88f86151a9ae6feea12a3c435c2f75 Mon Sep 17 00:00:00 2001
From: Mark Michelson <mmichelson@digium.com>
Date: Tue, 10 Feb 2009 23:21:03 +0000
Subject: [PATCH] Merged revisions 174805 via svnmerge from
 https://origsvn.digium.com/svn/asterisk/trunk

........
r174805 | mmichelson | 2009-02-10 17:17:03 -0600 (Tue, 10 Feb 2009) | 11 lines

Fix potential for stack overflows in app_chanspy.c

When using the 'g' or 'e' options, the stack allocations that
were used could cause a stack overflow if a spyer stayed on the
line long enough without actually successfully spying on anyone.

The problem has been corrected by using static buffers and copying
the contents of the appropriate strings into them instead of using
functions like alloca or ast_strdupa


........


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.6.1@174823 65c4cc65-6c06-0410-ace0-fbb531ad65f3
---
 apps/app_chanspy.c | 55 +++++++++++++++++++---------------------------
 1 file changed, 22 insertions(+), 33 deletions(-)

diff --git a/apps/app_chanspy.c b/apps/app_chanspy.c
index 7e79eacf0a..310e14ab51 100644
--- a/apps/app_chanspy.c
+++ b/apps/app_chanspy.c
@@ -713,22 +713,9 @@ static int common_exec(struct ast_channel *chan, struct ast_flags *flags,
 			 chanspy_ds_free(peer_chanspy_ds), prev = peer,
 		     peer_chanspy_ds = next_chanspy_ds ? next_chanspy_ds : 
 			 	next_channel(chan, prev, spec, exten, context, &chanspy_ds), next_chanspy_ds = NULL) {
-			const char *group;
 			int igrp = !mygroup;
-			char *groups[NUM_SPYGROUPS];
-			char *mygroups[NUM_SPYGROUPS];
-			int num_groups = 0;
-			char dup_group[512];
-			int num_mygroups = 0;
-			char *dup_mygroup;
-			int x;
-			int y;
-			char *s;
-			char *buffer;
-			char *end;
-			char *ext;
-			char *form_enforced;
 			int ienf = !myenforced;
+			char *s;
 
 			peer = peer_chanspy_ds->chan;
 
@@ -757,7 +744,16 @@ static int common_exec(struct ast_channel *chan, struct ast_flags *flags,
 			}
 
 			if (mygroup) {
-				dup_mygroup = ast_strdupa(mygroup);
+				int num_groups = 0;
+				int num_mygroups = 0;
+				char dup_group[512];
+				char dup_mygroup[512];
+				char *groups[NUM_SPYGROUPS];
+				char *mygroups[NUM_SPYGROUPS];
+				const char *group;
+				int x;
+				int y;
+				ast_copy_string(dup_mygroup, mygroup, sizeof(dup_mygroup));
 				num_mygroups = ast_app_separate_args(dup_mygroup, ':', mygroups,
 					ARRAY_LEN(mygroups));
 
@@ -783,35 +779,28 @@ static int common_exec(struct ast_channel *chan, struct ast_flags *flags,
 			}
 
 			if (myenforced) {
+				char ext[AST_CHANNEL_NAME + 3];
+				char buffer[512];
+				char *end;
 
-				/* We don't need to allocate more space than just the
-				length of (peer->name) for ext as we will cut the
-				channel name's ending before copying into ext */
+				snprintf(buffer, sizeof(buffer) - 1, ":%s:", myenforced);
 
-				ext = alloca(strlen(peer->name));
-
-				form_enforced = alloca(strlen(myenforced) + 3);
-
-				strcpy(form_enforced, ":");
-				strcat(form_enforced, myenforced);
-				strcat(form_enforced, ":");
-
-				buffer = ast_strdupa(peer->name);
-				
-				if ((end = strchr(buffer, '-'))) {
+				ast_copy_string(ext + 1, peer->name, sizeof(ext) - 1);
+				if ((end = strchr(ext, '-'))) {
 					*end++ = ':';
 					*end = '\0';
 				}
 
-				strcpy(ext, ":");
-				strcat(ext, buffer);
+				ext[0] = ':';
 
-				if (strcasestr(form_enforced, ext))
+				if (strcasestr(buffer, ext)) {
 					ienf = 1;
+				}
 			}
 
-			if (!ienf)
+			if (!ienf) {
 				continue;
+			}
 
 			strcpy(peer_name, "spy-");
 			strncat(peer_name, peer->name, AST_NAME_STRLEN - 4 - 1);