From: Matthew Jordan <mjordan@digium.com>
Date: Mon, 9 Apr 2012 19:42:53 +0000 (+0000)
Subject: Change SHARED function to use a safe traversal when modifying a variable
X-Git-Tag: 10.5.0-rc1~71
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3c880e779f80027fb0d01311671ddfc506147cc0;p=thirdparty%2Fasterisk.git

Change SHARED function to use a safe traversal when modifying a variable

When the SHARED function modifies a variable, it removes it from its list of
variables and reinserts the new value at the head of the list of variables.
Doing this inside a standard list traversal can be dangerous, as the
standard list traversal does not account for the list being changed.  While
the code in question should not cause a use after free violation due to its
breaking out of the loop after freeing the variable, it could lead to a
maintenance issue if the loop was modified.  This also fixes a violation
reported by a static analysis tool, which also makes this code easier to
maintain in the future.
........

Merged revisions 361657 from http://svn.asterisk.org/svn/asterisk/branches/1.8


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/10@361658 65c4cc65-6c06-0410-ace0-fbb531ad65f3
---

diff --git a/funcs/func_global.c b/funcs/func_global.c
index 6b158aafbb..201f075d47 100644
--- a/funcs/func_global.c
+++ b/funcs/func_global.c
@@ -243,14 +243,15 @@ static int shared_write(struct ast_channel *chan, const char *cmd, char *data, c
 	varshead = varstore->data;
 
 	/* Protected by the channel lock */
-	AST_LIST_TRAVERSE(varshead, var, entries) {
+	AST_LIST_TRAVERSE_SAFE_BEGIN(varshead, var, entries) {
 		/* If there's a previous value, remove it */
 		if (!strcmp(args.var, ast_var_name(var))) {
-			AST_LIST_REMOVE(varshead, var, entries);
+			AST_LIST_REMOVE_CURRENT(entries);
 			ast_var_delete(var);
 			break;
 		}
 	}
+	AST_LIST_TRAVERSE_SAFE_END;
 
 	var = ast_var_assign(args.var, S_OR(value, ""));
 	AST_LIST_INSERT_HEAD(varshead, var, entries);