From 50f06b3efb638efb0abd95dc62dca05ae67882c2 Mon Sep 17 00:00:00 2001 From: Nick Wellnhofer Date: Fri, 7 Aug 2020 21:54:27 +0200 Subject: [PATCH] Fix out-of-bounds read with 'xmllint --htmlout' Make sure that truncated UTF-8 sequences don't cause an out-of-bounds array access. Thanks to @SuhwanSong and the Agency for Defense Development (ADD) for the report. Fixes #178. CVE: CVE-2020-24977 Upstream-Status: Backport [https://gitlab.gnome.org/GNOME/libxml2/-/commit/50f06b3efb638efb0abd95dc62dca05ae67882c2] Signed-off-by: Ovidiu Panait --- xmllint.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/xmllint.c b/xmllint.c index f6a8e463..c647486f 100644 --- a/xmllint.c +++ b/xmllint.c @@ -528,6 +528,12 @@ static void xmlHTMLEncodeSend(void) { char *result; + /* + * xmlEncodeEntitiesReentrant assumes valid UTF-8, but the buffer might + * end with a truncated UTF-8 sequence. This is a hack to at least avoid + * an out-of-bounds read. + */ + memset(&buffer[sizeof(buffer)-4], 0, 4); result = (char *) xmlEncodeEntitiesReentrant(NULL, BAD_CAST buffer); if (result) { xmlGenericError(xmlGenericErrorContext, "%s", result); -- 2.17.1