There's a flaw in libxml2 in versions before 2.9.11. An attacker who is able to submit a crafted file to be processed by an application linked with libxml2 could trigger a use-after-free. The greatest impact from this flaw is to confidentiality, integrity, and availability.
Upstream-Status: Backport [from fedora: https://bugzilla.redhat.com/show_bug.cgi?id=1954243] Signed-off-by: Jasper Orschulko <jas...@fancydomain.eu> --- .../libxml/libxml2/CVE-2021-3518.patch | 108 ++++++++++++++++++ meta/recipes-core/libxml/libxml2_2.9.10.bb | 1 + 2 files changed, 109 insertions(+) create mode 100644 meta/recipes-core/libxml/libxml2/CVE-2021-3518.patch diff --git a/meta/recipes-core/libxml/libxml2/CVE-2021-3518.patch b/meta/recipes-core/libxml/libxml2/CVE-2021-3518.patch new file mode 100644 index 0000000000..c22cccf1b1 --- /dev/null +++ b/meta/recipes-core/libxml/libxml2/CVE-2021-3518.patch @@ -0,0 +1,108 @@ +From ac82a514e16eb81b4506e2cba1a1ee45b9f025b5 Mon Sep 17 00:00:00 2001 +From: Nick Wellnhofer <wellnho...@aevum.de> +Date: Wed, 10 Jun 2020 16:34:52 +0200 +Subject: [PATCH 1/2] Don't recurse into xi:include children in + xmlXIncludeDoProcess + +Otherwise, nested xi:include nodes might result in a use-after-free +if XML_PARSE_NOXINCNODE is specified. + +Found with libFuzzer and ASan. + +The upstream patch 752e5f71d7cea2ca5a7e7c0b8f72ed04ce654be4 has been modified, +as to avoid unnecessary modifications to fallback files. + +Signed-off-by: Jasper Orschulko <jasper.orschu...@iris-sensing.com> +--- + xinclude.c | 24 ++++++++++-------------- + 1 file changed, 10 insertions(+), 14 deletions(-) + +diff --git a/xinclude.c b/xinclude.c +index ba850fa5..f260c1a7 100644 +--- a/xinclude.c ++++ b/xinclude.c +@@ -2392,21 +2392,19 @@ xmlXIncludeDoProcess(xmlXIncludeCtxtPtr ctxt, xmlDocPtr doc, xmlNodePtr tree) { + * First phase: lookup the elements in the document + */ + cur = tree; +- if (xmlXIncludeTestNode(ctxt, cur) == 1) +- xmlXIncludePreProcessNode(ctxt, cur); + while ((cur != NULL) && (cur != tree->parent)) { + /* TODO: need to work on entities -> stack */ +- if ((cur->children != NULL) && +- (cur->children->type != XML_ENTITY_DECL) && +- (cur->children->type != XML_XINCLUDE_START) && +- (cur->children->type != XML_XINCLUDE_END)) { +- cur = cur->children; +- if (xmlXIncludeTestNode(ctxt, cur)) +- xmlXIncludePreProcessNode(ctxt, cur); +- } else if (cur->next != NULL) { ++ if (xmlXIncludeTestNode(ctxt, cur) == 1) { ++ xmlXIncludePreProcessNode(ctxt, cur); ++ } else if ((cur->children != NULL) && ++ (cur->children->type != XML_ENTITY_DECL) && ++ (cur->children->type != XML_XINCLUDE_START) && ++ (cur->children->type != XML_XINCLUDE_END)) { ++ cur = cur->children; ++ continue; ++ } ++ if (cur->next != NULL) { + cur = cur->next; +- if (xmlXIncludeTestNode(ctxt, cur)) +- xmlXIncludePreProcessNode(ctxt, cur); + } else { + if (cur == tree) + break; +@@ -2416,8 +2414,6 @@ xmlXIncludeDoProcess(xmlXIncludeCtxtPtr ctxt, xmlDocPtr doc, xmlNodePtr tree) { + break; /* do */ + if (cur->next != NULL) { + cur = cur->next; +- if (xmlXIncludeTestNode(ctxt, cur)) +- xmlXIncludePreProcessNode(ctxt, cur); + break; /* do */ + } + } while (cur != NULL); +-- +2.32.0 + + +From 3ad5ac1e39e3cd42f838c1cd27ffd4e9b79e6121 Mon Sep 17 00:00:00 2001 +From: Nick Wellnhofer <wellnho...@aevum.de> +Date: Thu, 22 Apr 2021 19:26:28 +0200 +Subject: [PATCH 2/2] Fix user-after-free with `xmllint --xinclude --dropdtd` + +The --dropdtd option can leave dangling pointers in entity reference +nodes. Make sure to skip these nodes when processing XIncludes. + +This also avoids scanning entity declarations and even modifying +them inadvertently during XInclude processing. + +Move from a block list to an allow list approach to avoid descending +into other node types that can't contain elements. + +Fixes #237. + +Signed-off-by: Jasper Orschulko <jasper.orschu...@iris-sensing.com> +--- + xinclude.c | 5 ++--- + 1 file changed, 2 insertions(+), 3 deletions(-) + +diff --git a/xinclude.c b/xinclude.c +index f260c1a7..d7648529 100644 +--- a/xinclude.c ++++ b/xinclude.c +@@ -2397,9 +2397,8 @@ xmlXIncludeDoProcess(xmlXIncludeCtxtPtr ctxt, xmlDocPtr doc, xmlNodePtr tree) { + if (xmlXIncludeTestNode(ctxt, cur) == 1) { + xmlXIncludePreProcessNode(ctxt, cur); + } else if ((cur->children != NULL) && +- (cur->children->type != XML_ENTITY_DECL) && +- (cur->children->type != XML_XINCLUDE_START) && +- (cur->children->type != XML_XINCLUDE_END)) { ++ ((cur->type == XML_DOCUMENT_NODE) || ++ (cur->type == XML_ELEMENT_NODE))) { + cur = cur->children; + continue; + } +-- +2.32.0 + diff --git a/meta/recipes-core/libxml/libxml2_2.9.10.bb b/meta/recipes-core/libxml/libxml2_2.9.10.bb index 097613fb28..b5fb3e6315 100644 --- a/meta/recipes-core/libxml/libxml2_2.9.10.bb +++ b/meta/recipes-core/libxml/libxml2_2.9.10.bb @@ -25,6 +25,7 @@ SRC_URI = "http://www.xmlsoft.org/sources/libxml2-${PV}.tar.gz;name=libtar \ file://CVE-2020-24977.patch \ file://CVE-2021-3517.patch \ file://CVE-2021-3537.patch \ + file://CVE-2021-3518.patch \ " SRC_URI[libtar.md5sum] = "10942a1dc23137a8aa07f0639cbfece5" -- 2.32.0
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