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: http://svn.digium.com/svn/asterisk/branches/1.6.0@174820 f38db490-d61c-443f-a65b-d21fe96a405b

1 files changed, 17 insertions, 28 deletions

diff --git a/apps/app_chanspy.c b/apps/app_chanspy.c
index 54960281f..d897f4b08 100644
--- a/apps/app_chanspy.c
+++ b/apps/app_chanspy.c
@@ -613,18 +613,9 @@ static int common_exec(struct ast_channel *chan, const 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[25];
-			int num_groups = 0;
-			char dup_group[512];
-			int x;
-			char *s;
-			char *buffer;
-			char *end;
-			char *ext;
-			char *form_enforced;
 			int ienf = !myenforced;
+			char *s;
 
 			peer = peer_chanspy_ds->chan;
 
@@ -653,6 +644,11 @@ static int common_exec(struct ast_channel *chan, const struct ast_flags *flags,
 			}
 
 			if (mygroup) {
+				int num_groups = 0;
+				char dup_group[512];
+				char *groups[25];
+				const char *group;
+				int x;
 				if ((group = pbx_builtin_getvar_helper(peer, "SPYGROUP"))) {
 					ast_copy_string(dup_group, group, sizeof(dup_group));
 					num_groups = ast_app_separate_args(dup_group, ':', groups,
@@ -673,35 +669,28 @@ static int common_exec(struct ast_channel *chan, const 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 */
-
-				ext = alloca(strlen(peer->name));
-
-				form_enforced = alloca(strlen(myenforced) + 3);
+				snprintf(buffer, sizeof(buffer) - 1, ":%s:", myenforced);
 
-				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);