Software / code / prosody
Changeset
12201:e5e0ab93d7f4 0.11
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.
| author | Kim Alvefur <zash@zash.se> |
|---|---|
| date | Thu, 20 Jan 2022 09:57:20 +0100 |
| parents | 12182:5e21cf21d398 |
| children | 12202:ebeb4d959fb3 |
| files | util/xml.lua |
| diffstat | 1 files changed, 4 insertions(+), 5 deletions(-) [+] |
line wrap: on
line diff
--- a/util/xml.lua Thu Jan 13 12:18:49 2022 +0000 +++ b/util/xml.lua Thu Jan 20 09:57:20 2022 +0100 @@ -65,27 +65,26 @@ 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();
