malloc-fail: Fix OOB read after xmlRegGetCounter

Found with libFuzzer, see #344.

(cherry picked from commit 1743c4c3fc58cf38ecce68db9de51d0f3651e033)

I also copied the error label from
e64653c0e7975594e27d7de2ed4be062c1e4ad03 to fix the build failure.

Bug: http://b/274231102
Test: TreeHugger
Change-Id: I3bad3e03092e17a761cb6e299aff848ebd35b6f4

1 files changed, 28 insertions, 0 deletions

diff --git a/xmlregexp.c b/xmlregexp.c
index d255fbf0..6234a879 100644
--- a/xmlregexp.c
+++ b/xmlregexp.c
@@ -1641,6 +1641,8 @@ xmlFAGenerateTransitions(xmlRegParserCtxtPtr ctxt, xmlRegStatePtr from,
 			return(-1);
 		    inter = ctxt->state;
 		    counter = xmlRegGetCounter(ctxt);
+                    if (counter < 0)
+                        return(-1);
 		    ctxt->counters[counter].min = atom->min - 1;
 		    ctxt->counters[counter].max = atom->max - 1;
 		    /* count the number of times we see it again */
@@ -1659,6 +1661,8 @@ xmlFAGenerateTransitions(xmlRegParserCtxtPtr ctxt, xmlRegStatePtr from,
 		     * epsilon transition.
 		     */
 		    counter = xmlRegGetCounter(ctxt);
+                    if (counter < 0)
+                        return(-1);
 		    ctxt->counters[counter].min = atom->min - 1;
 		    ctxt->counters[counter].max = atom->max - 1;
 		    /* count the number of times we see it again */
@@ -5924,6 +5928,8 @@ xmlAutomataNewCountTrans2(xmlAutomataPtr am, xmlAutomataStatePtr from,
      * associate a counter to the transition.
      */
     counter = xmlRegGetCounter(am);
+    if (counter < 0)
+        goto error;
     am->counters[counter].min = min;
     am->counters[counter].max = max;
 
@@ -5943,6 +5949,10 @@ xmlAutomataNewCountTrans2(xmlAutomataPtr am, xmlAutomataStatePtr from,
     if (min == 0)
 	xmlFAGenerateEpsilonTransition(am, from, to);
     return(to);
+
+error:
+    xmlRegFreeAtom(atom);
+    return(NULL);
 }
 
 /**
@@ -5990,6 +6000,8 @@ xmlAutomataNewCountTrans(xmlAutomataPtr am, xmlAutomataStatePtr from,
      * associate a counter to the transition.
      */
     counter = xmlRegGetCounter(am);
+    if (counter < 0)
+        goto error;
     am->counters[counter].min = min;
     am->counters[counter].max = max;
 
@@ -6009,6 +6021,10 @@ xmlAutomataNewCountTrans(xmlAutomataPtr am, xmlAutomataStatePtr from,
     if (min == 0)
 	xmlFAGenerateEpsilonTransition(am, from, to);
     return(to);
+
+error:
+    xmlRegFreeAtom(atom);
+    return(NULL);
 }
 
 /**
@@ -6076,6 +6092,8 @@ xmlAutomataNewOnceTrans2(xmlAutomataPtr am, xmlAutomataStatePtr from,
      * associate a counter to the transition.
      */
     counter = xmlRegGetCounter(am);
+    if (counter < 0)
+        goto error;
     am->counters[counter].min = 1;
     am->counters[counter].max = 1;
 
@@ -6088,6 +6106,10 @@ xmlAutomataNewOnceTrans2(xmlAutomataPtr am, xmlAutomataStatePtr from,
     xmlRegAtomPush(am, atom);
     am->state = to;
     return(to);
+
+error:
+    xmlRegFreeAtom(atom);
+    return(NULL);
 }
 
 
@@ -6135,6 +6157,8 @@ xmlAutomataNewOnceTrans(xmlAutomataPtr am, xmlAutomataStatePtr from,
      * associate a counter to the transition.
      */
     counter = xmlRegGetCounter(am);
+    if (counter < 0)
+        goto error;
     am->counters[counter].min = 1;
     am->counters[counter].max = 1;
 
@@ -6147,6 +6171,10 @@ xmlAutomataNewOnceTrans(xmlAutomataPtr am, xmlAutomataStatePtr from,
     xmlRegAtomPush(am, atom);
     am->state = to;
     return(to);
+
+error:
+    xmlRegFreeAtom(atom);
+    return(NULL);
 }
 
 /**