From 89f9e077d7fce488c1cc0644cc152a6c101aae02 Mon Sep 17 00:00:00 2001
From: Matthew Jordan <mjordan@digium.com>
Date: Wed, 2 Jan 2013 22:10:32 +0000
Subject: [PATCH] Prevent crashes from occurring when reading from data sources
with large values
When reading configuration data from an Asterisk .conf file or when pulling
data from an Asterisk RealTime backend, Asterisk was copying the data on the
stack for manipulation. Unfortunately, it is possible to read configuration
data or realtime data from some data source that provides a large blob of
characters. This could potentially cause a crash via a stack overflow.
This patch prevents large sets of data from being read from an ARA backend or
from an Asterisk conf file.
(issue ASTERISK-20658)
Reported by: wdoekes
Tested by: wdoekes, mmichelson
patches:
* issueA20658_dont_process_overlong_config_lines.patch uploaded by wdoekes (license 5674)
* issueA20658_func_realtime_limit.patch uploaded by wdoekes (license 5674)
........
Merged revisions 378375 from http://svn.asterisk.org/svn/asterisk/branches/1.8
........
Merged revisions 378376 from http://svn.asterisk.org/svn/asterisk/branches/11
git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@378377 65c4cc65-6c06-0410-ace0-fbb531ad65f3
---
funcs/func_realtime.c | 17 +++++++++++++++++
main/config.c | 11 +++++++++++
2 files changed, 28 insertions(+)
diff --git a/funcs/func_realtime.c b/funcs/func_realtime.c
index bd4b37dfe0..886b5b4566 100644
--- a/funcs/func_realtime.c
+++ b/funcs/func_realtime.c
@@ -219,6 +219,13 @@ static int function_realtime_read(struct ast_channel *chan, const char *cmd, cha
/* add space for delimiters and final '\0' */
resultslen += n * (strlen(args.delim1) + strlen(args.delim2)) + 1;
+ if (resultslen > len) {
+ ast_log(LOG_WARNING, "Failed to fetch. Realtime data is too large: need %zu, have %zu.\n", resultslen, len);
+ return -1;
+ }
+
+ /* len is going to be sensible, so we don't need to check for stack
+ * overflows here. */
out = ast_str_alloca(resultslen);
for (var = head; var; var = var->next)
ast_str_append(&out, 0, "%s%s%s%s", var->name, args.delim2, var->value, args.delim1);
@@ -439,6 +446,16 @@ static int function_realtime_readdestroy(struct ast_channel *chan, const char *c
/* add space for delimiters and final '\0' */
resultslen += n * (strlen(args.delim1) + strlen(args.delim2)) + 1;
+ if (resultslen > len) {
+ /* Unfortunately this does mean that we cannot destroy the row
+ * anymore. But OTOH, we're not destroying someones data without
+ * giving him the chance to look at it. */
+ ast_log(LOG_WARNING, "Failed to fetch/destroy. Realtime data is too large: need %zu, have %zu.\n", resultslen, len);
+ return -1;
+ }
+
+ /* len is going to be sensible, so we don't need to check for stack
+ * overflows here. */
out = ast_str_alloca(resultslen);
for (var = head; var; var = var->next) {
ast_str_append(&out, 0, "%s%s%s%s", var->name, args.delim2, var->value, args.delim1);
diff --git a/main/config.c b/main/config.c
index f56421ee04..cf2b84c72b 100644
--- a/main/config.c
+++ b/main/config.c
@@ -1646,6 +1646,17 @@ static struct ast_config *config_text_file_load(const char *database, const char
while (!feof(f)) {
lineno++;
if (fgets(buf, sizeof(buf), f)) {
+ /* Skip lines that are too long */
+ if (strlen(buf) == sizeof(buf) - 1 && buf[sizeof(buf) - 1] != '\n') {
+ ast_log(LOG_WARNING, "Line %d too long, skipping. It begins with: %.32s...\n", lineno, buf);
+ while (fgets(buf, sizeof(buf), f)) {
+ if (strlen(buf) != sizeof(buf) - 1 || buf[sizeof(buf) - 1] == '\n') {
+ break;
+ }
+ }
+ continue;
+ }
+
if (ast_test_flag(&flags, CONFIG_FLAG_WITHCOMMENTS) && lline_buffer && ast_str_strlen(lline_buffer)) {
CB_ADD(&comment_buffer, ast_str_buffer(lline_buffer)); /* add the current lline buffer to the comment buffer */
ast_str_reset(lline_buffer); /* erase the lline buffer */
--
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