| From 29115868c92c81a4119b05ea95b3c91608a0b6e8 Mon Sep 17 00:00:00 2001 |
| From: Nick Wellnhofer <wellnhofer@aevum.de> |
| Date: Mon, 30 Jul 2018 12:54:38 +0200 |
| Subject: [PATCH] Fix nullptr deref with XPath logic ops |
| |
| If the XPath stack is corrupted, for example by a misbehaving extension |
| function, the "and" and "or" XPath operators could dereference NULL |
| pointers. Check that the XPath stack isn't empty and optimize the |
| logic operators slightly. |
| |
| Closes: https://gitlab.gnome.org/GNOME/libxml2/issues/5 |
| |
| Also see |
| https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=901817 |
| https://bugzilla.redhat.com/show_bug.cgi?id=1595985 |
| |
| This is CVE-2018-14404. |
| |
| Thanks to Guy Inbar for the report. |
| |
| CVE: CVE-2018-14404 |
| Upstream-Status: Backport [https://gitlab.gnome.org/GNOME/libxml2/commit/a436374994c47b12d5de1b8b1d191a098fa23594] |
| Signed-off-by: Sinan Kaya <okaya@kernel.org> |
| --- |
| xpath.c | 10 ++++------ |
| 1 file changed, 4 insertions(+), 6 deletions(-) |
| |
| diff --git a/xpath.c b/xpath.c |
| index 35274731..3fcdc9e1 100644 |
| --- a/xpath.c |
| +++ b/xpath.c |
| @@ -13337,9 +13337,8 @@ xmlXPathCompOpEval(xmlXPathParserContextPtr ctxt, xmlXPathStepOpPtr op) |
| return(0); |
| } |
| xmlXPathBooleanFunction(ctxt, 1); |
| - arg1 = valuePop(ctxt); |
| - arg1->boolval &= arg2->boolval; |
| - valuePush(ctxt, arg1); |
| + if (ctxt->value != NULL) |
| + ctxt->value->boolval &= arg2->boolval; |
| xmlXPathReleaseObject(ctxt->context, arg2); |
| return (total); |
| case XPATH_OP_OR: |
| @@ -13363,9 +13362,8 @@ xmlXPathCompOpEval(xmlXPathParserContextPtr ctxt, xmlXPathStepOpPtr op) |
| return(0); |
| } |
| xmlXPathBooleanFunction(ctxt, 1); |
| - arg1 = valuePop(ctxt); |
| - arg1->boolval |= arg2->boolval; |
| - valuePush(ctxt, arg1); |
| + if (ctxt->value != NULL) |
| + ctxt->value->boolval |= arg2->boolval; |
| xmlXPathReleaseObject(ctxt->context, arg2); |
| return (total); |
| case XPATH_OP_EQUAL: |
| -- |
| 2.19.0 |
| |