[libxml2] Enable more undefined behavior sanitizers

[Nick Wellnhofer <nwellnhof src gnome org>]

commit db0c0450db66606f4068b237ba233e97e0b16a69
Author: Nick Wellnhofer <wellnhofer aevum de>
Date:   Sat Nov 2 15:14:10 2019 +0100

    Enable more undefined behavior sanitizers
    
    Minor fix to xmlStringLenGetNodeList to avoid a pointer overflow
    during API test.
    
    Enable pointer-overflow and unsigned-integer-overflow sanitizers in CI
    tests. Technically, unsigned integer overflows aren't undefined
    behavior, but they typically indicate programming errors. Some hash
    functions that really require unsigned integer overflows have already
    been annotated.

 .gitlab-ci.yml | 2 +-
 .travis.yml    | 2 +-
 tree.c         | 4 +++-
 3 files changed, 5 insertions(+), 3 deletions(-)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 78784fba..71f66e0b 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -32,7 +32,7 @@ clang:asan:
   variables:
     CONFIG: "--without-python"
     CC: clang
-    CFLAGS: "-O2 -g -fno-omit-frame-pointer -fsanitize=address,undefined -fno-sanitize=pointer-overflow 
-fno-sanitize-recover=all -Wno-error=cast-align"
+    CFLAGS: "-O2 -g -fno-omit-frame-pointer -fsanitize=address,undefined,unsigned-integer-overflow 
-fno-sanitize-recover=all -Wno-error=cast-align"
     UBSAN_OPTIONS: "print_stacktrace=1"
 
 clang:msan:
diff --git a/.travis.yml b/.travis.yml
index 68fe5abd..358e8cbf 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -16,7 +16,7 @@ matrix:
       sudo: required
       dist: trusty
       env: CONFIG="--without-python"
-           CFLAGS="-O2 -g -fno-omit-frame-pointer -fsanitize=address,undefined 
-fno-sanitize=float-divide-by-zero,pointer-overflow -fno-sanitize-recover=all -Werror -Wno-error=cast-align"
+           CFLAGS="-O2 -g -fno-omit-frame-pointer -fsanitize=address,undefined,unsigned-integer-overflow 
-fno-sanitize-recover=all -Werror -Wno-error=cast-align"
            UBSAN_OPTIONS=print_stacktrace=1
 script: sh autogen.sh $CONFIG && make -j2 V=1 && make check
 git:
diff --git a/tree.c b/tree.c
index 08b1a500..070670f1 100644
--- a/tree.c
+++ b/tree.c
@@ -1276,12 +1276,14 @@ xmlStringLenGetNodeList(const xmlDoc *doc, const xmlChar *value, int len) {
     xmlNodePtr ret = NULL, last = NULL;
     xmlNodePtr node;
     xmlChar *val;
-    const xmlChar *cur = value, *end = cur + len;
+    const xmlChar *cur, *end;
     const xmlChar *q;
     xmlEntityPtr ent;
     xmlBufPtr buf;
 
     if (value == NULL) return(NULL);
+    cur = value;
+    end = cur + len;
 
     buf = xmlBufCreateSize(0);
     if (buf == NULL) return(NULL);