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authorKim Alvefur <zash@zash.se>2022-01-20 09:57:20 +0100
committerKim Alvefur <zash@zash.se>2022-01-20 09:57:20 +0100
commitd17619344dda05f9bc9b3f98a0c82f2f68939605 (patch)
tree523dfd5c7ee5a52ada870d12a315bca4f5ab3a61
parent695fb9b8fb478cef3dd5ec5e35d704cdba5dffae (diff)
downloadprosody-d17619344dda05f9bc9b3f98a0c82f2f68939605.tar.gz
prosody-d17619344dda05f9bc9b3f98a0c82f2f68939605.zip
util.xml: Break reference to help the GC (fix #1711)
LuaExpat uses a registry reference to track handlers, which makes it so that an upvalue like this creates a reference loop that keeps the parser and its handlers from being garbage collected. The same issue has affected util.xmppstream in the past. Code for checking: local xml_parse = require"util.xml".parse; for i = 1, 10000 do xml_parse("<root/>") end collectgarbage(); collectgarbage(); print(collectgarbage("count"), "KiB"); A future release of LuaExpat may fix the underlying issue there.
-rw-r--r--util/xml.lua9
1 files changed, 4 insertions, 5 deletions
diff --git a/util/xml.lua b/util/xml.lua
index 700da1d4..72f1a26b 100644
--- a/util/xml.lua
+++ b/util/xml.lua
@@ -65,27 +65,26 @@ local parse_xml = (function()
function handler:EndElement()
stanza:up();
end
- local parser;
-- SECURITY: These two handlers, especially the Doctype one, are required to prevent exploits such as Billion Laughs.
function handler:StartDoctypeDecl()
- if not parser.stop or not parser:stop() then
+ if not self.stop or not self:stop() then
error("Failed to abort parsing");
end
end
function handler:ProcessingInstruction()
- if not parser.stop or not parser:stop() then
+ if not self.stop or not self:stop() then
error("Failed to abort parsing");
end
end
if not options or not options.allow_comments then
-- NOTE: comments are generally harmless and can be useful when parsing configuration files or other data, even user-provided data
function handler:Comment()
- if not parser.stop or not parser:stop() then
+ if not self.stop or not self:stop() then
error("Failed to abort parsing");
end
end
end
- parser = lxp.new(handler, ns_separator);
+ local parser = lxp.new(handler, ns_separator);
local ok, err, line, col = parser:parse(xml);
if ok then ok, err, line, col = parser:parse(); end
--parser:close();