From 4b5d11ec1779665fe0792d38cfe39bff872c15d8 Mon Sep 17 00:00:00 2001
From: Kevin Harwell <kharwell@digium.com>
Date: Fri, 16 Nov 2018 14:45:23 -0600
Subject: [PATCH] func_strings: HASHKEY - negative array index can cause
corruption
This patch makes it so only matching non-empty key names, and keys created by
the HASH function are eligible for inclusion in the comma separated string. It
also fixes a bug where it was possible to write to a negative index if the
result buffer was empty.
ASTERISK-28159
patches:
ASTERISK-28159.diff submitted by Michael Walton (license 6502)
Change-Id: I6e57fe7307dfd856271753aed5ba64c59b511487
---
funcs/func_strings.c | 54 +++++++++++++++++++++++++++++++++-----------
1 file changed, 41 insertions(+), 13 deletions(-)
diff --git a/funcs/func_strings.c b/funcs/func_strings.c
index cb253850d6..7afc40e384 100644
--- a/funcs/func_strings.c
+++ b/funcs/func_strings.c
@@ -1089,10 +1089,33 @@ static int array(struct ast_channel *chan, const char *cmd, char *var,
return 0;
}
+static const char *get_key(const struct ast_str *prefix, const struct ast_var_t *var)
+{
+ const char *prefix_name = ast_str_buffer(prefix);
+ const char *var_name = ast_var_name(var);
+ int prefix_len;
+ int var_len;
+
+ if (ast_strlen_zero(var_name)) {
+ return NULL;
+ }
+
+ prefix_len = ast_str_strlen(prefix);
+ var_len = strlen(var_name);
+
+ /*
+ * Make sure we only match on non-empty, hash function created keys. If valid
+ * then return a pointer to the variable that's just after the prefix.
+ */
+ return var_len > (prefix_len + 1) && var_name[var_len - 1] == '~' &&
+ strncmp(prefix_name, var_name, prefix_len) == 0 ? var_name + prefix_len : NULL;
+}
+
static int hashkeys_read(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
{
struct ast_var_t *newvar;
struct ast_str *prefix = ast_str_alloca(80);
+ size_t buf_len;
if (!chan) {
ast_log(LOG_WARNING, "No channel was provided to %s function.\n", cmd);
@@ -1103,15 +1126,19 @@ static int hashkeys_read(struct ast_channel *chan, const char *cmd, char *data,
memset(buf, 0, len);
AST_LIST_TRAVERSE(ast_channel_varshead(chan), newvar, entries) {
- if (strncmp(ast_str_buffer(prefix), ast_var_name(newvar), ast_str_strlen(prefix)) == 0) {
- /* Copy everything after the prefix */
- strncat(buf, ast_var_name(newvar) + ast_str_strlen(prefix), len - strlen(buf) - 1);
- /* Trim the trailing ~ */
+ const char *key = get_key(prefix, newvar);
+
+ if (key) {
+ strncat(buf, key, len - strlen(buf) - 1);
+ /* Replace the trailing ~ */
buf[strlen(buf) - 1] = ',';
}
}
/* Trim the trailing comma */
- buf[strlen(buf) - 1] = '\0';
+ buf_len = strlen(buf);
+ if (buf_len) {
+ buf[buf_len - 1] = '\0';
+ }
return 0;
}
@@ -1119,7 +1146,6 @@ static int hashkeys_read2(struct ast_channel *chan, const char *cmd, char *data,
{
struct ast_var_t *newvar;
struct ast_str *prefix = ast_str_alloca(80);
- char *tmp;
if (!chan) {
ast_log(LOG_WARNING, "No channel was provided to %s function.\n", cmd);
@@ -1129,17 +1155,19 @@ static int hashkeys_read2(struct ast_channel *chan, const char *cmd, char *data,
ast_str_set(&prefix, -1, HASH_PREFIX, data);
AST_LIST_TRAVERSE(ast_channel_varshead(chan), newvar, entries) {
- if (strncmp(ast_str_buffer(prefix), ast_var_name(newvar), ast_str_strlen(prefix)) == 0) {
- /* Copy everything after the prefix */
- ast_str_append(buf, len, "%s", ast_var_name(newvar) + ast_str_strlen(prefix));
- /* Trim the trailing ~ */
+ const char *key = get_key(prefix, newvar);
+
+ if (key) {
+ char *tmp;
+
+ ast_str_append(buf, len, "%s", key);
+ /* Replace the trailing ~ */
tmp = ast_str_buffer(*buf);
tmp[ast_str_strlen(*buf) - 1] = ',';
}
}
- /* Trim the trailing comma */
- tmp = ast_str_buffer(*buf);
- tmp[ast_str_strlen(*buf) - 1] = '\0';
+
+ ast_str_truncate(*buf, -1);
return 0;
}
--
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