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* docbook2mdoc: To avoid use after free, use TAILQ_FOREACH_SAFE(3) rather
@ 2019-03-24 23:49 schwarze
  0 siblings, 0 replies; only message in thread
From: schwarze @ 2019-03-24 23:49 UTC (permalink / raw)
  To: source

Log Message:
-----------
To avoid use after free, use TAILQ_FOREACH_SAFE(3) rather than
TAILQ_FOREACH(3) when deleting list elements during the iteration.
Factor out some repeated code into a new function pnode_printtitle().

Where pnode_print() calls per-element pnode_print*() functions,
call exactly one function per element and do everything that is
required inside, making the huge function pnode_print() slightly
smaller and the various pnode_print*() more self-contained.
In particular, call pnode_unlinksub() as close as possible to the
place where the processing justifying the deletion was done.

Modified Files:
--------------
    docbook2mdoc:
        docbook2mdoc.c

Revision Data
-------------
Index: docbook2mdoc.c
===================================================================
RCS file: /home/cvs/mdocml/docbook2mdoc/docbook2mdoc.c,v
retrieving revision 1.70
retrieving revision 1.71
diff -Ldocbook2mdoc.c -Ldocbook2mdoc.c -u -p -r1.70 -r1.71
--- docbook2mdoc.c
+++ docbook2mdoc.c
@@ -757,13 +757,13 @@ pnode_printpara(struct parse *p, struct 
 static void
 pnode_printrefsynopsisdiv(struct parse *p, struct pnode *pn)
 {
-	struct pnode	*pp;
+	struct pnode	*pp, *pq;
 
-	TAILQ_FOREACH(pp, &pn->childq, child)
-		if (pp->node == NODE_TITLE) {
+	TAILQ_FOREACH_SAFE(pp, &pn->childq, child, pq)
+		if (pp->node == NODE_TITLE)
 			pnode_unlink(pp);
-			return;
-		}
+
+	macro_line(p, "Sh SYNOPSIS");
 }
 
 /*
@@ -867,6 +867,7 @@ pnode_printciterefentry(struct parse *p,
 	else
 		macro_addnode(p, manvol, 0);
 	macro_close(p);
+	pnode_unlinksub(pn);
 }
 
 static void
@@ -891,6 +892,7 @@ pnode_printrefmeta(struct parse *p, stru
 	else
 		macro_addnode(p, manvol, 0);
 	macro_close(p);
+	pnode_unlink(pn);
 }
 
 static void
@@ -961,8 +963,8 @@ pnode_printmathfenced(struct parse *p, s
 		putchar(',');
 		pnode_print(p, pp);
 	}
-
 	printf("right %s ", pnode_getattr_raw(pn, ATTRKEY_CLOSE, ")"));
+	pnode_unlinksub(pn);
 }
 
 /*
@@ -995,6 +997,7 @@ pnode_printmath(struct parse *p, struct 
 
 	pp = TAILQ_NEXT(pp, child);
 	pnode_print(p, pp);
+	pnode_unlinksub(pn);
 }
 
 static void
@@ -1016,6 +1019,7 @@ pnode_printfuncprototype(struct parse *p
 			pnode_printparamdef(p, pp);
 
 	macro_line(p, "Fc");
+	pnode_unlinksub(pn);
 }
 
 /*
@@ -1051,6 +1055,7 @@ pnode_printarg(struct parse *p, struct p
 		if (isrep && pp->node == NODE_TEXT)
 			macro_addarg(p, "...", 0);
 	}
+	pnode_unlinksub(pn);
 }
 
 static void
@@ -1101,6 +1106,7 @@ pnode_printgroup(struct parse *p, struct
 	}
 	if (sv)
 		macro_close(p);
+	pnode_unlinksub(pn);
 }
 
 static void
@@ -1112,10 +1118,9 @@ pnode_printprologue(struct parse *p, str
 		pnode_findfirst(p->root, NODE_REFMETA);
 
 	macro_line(p, "Dd $Mdocdate" "$");
-	if (pp != NULL) {
+	if (pp != NULL)
 		pnode_printrefmeta(p, pp);
-		pnode_unlink(pp);
-	} else {
+	else {
 		macro_open(p, "Dt");
 		macro_addarg(p,
 		    pnode_getattr_raw(p->root, ATTRKEY_ID, "UNKNOWN"), 0);
@@ -1154,6 +1159,21 @@ pnode_printvarlistentry(struct parse *p,
 	TAILQ_FOREACH(pp, &pn->childq, child)
 		if (pp->node != NODE_TERM)
 			pnode_print(p, pp);
+	pnode_unlinksub(pn);
+}
+
+static void
+pnode_printtitle(struct parse *p, struct pnode *pn)
+{
+	struct pnode	*pp, *pq;
+
+	TAILQ_FOREACH_SAFE(pp, &pn->childq, child, pq) {
+		if (pp->node == NODE_TITLE) {
+			pnode_printpara(p, pp);
+			pnode_print(p, pp);
+			pnode_unlink(pp);
+		}
+	}
 }
 
 static void
@@ -1167,6 +1187,7 @@ pnode_printrow(struct parse *p, struct p
 		pnode_print(p, pp);
 	}
 	macro_line(p, "El");
+	pnode_unlink(pn);
 }
 
 static void
@@ -1174,20 +1195,14 @@ pnode_printtable(struct parse *p, struct
 {
 	struct pnode	*pp;
 
-	TAILQ_FOREACH(pp, &pn->childq, child) {
-		if (pp->node == NODE_TITLE) {
-			pnode_printpara(p, pp);
-			pnode_print(p, pp);
-			pnode_unlink(pp);
-		}
-	}
+	pnode_printtitle(p, pn);
 	macro_line(p, "Bl -ohang");
 	while ((pp = pnode_findfirst(pn, NODE_ROW)) != NULL) {
 		macro_line(p, "It Table Row");
 		pnode_printrow(p, pp);
-		pnode_unlink(pp);
 	}
 	macro_line(p, "El");
+	pnode_unlinksub(pn);
 }
 
 static void
@@ -1195,13 +1210,7 @@ pnode_printlist(struct parse *p, struct 
 {
 	struct pnode	*pp;
 
-	TAILQ_FOREACH(pp, &pn->childq, child) {
-		if (pp->node == NODE_TITLE) {
-			pnode_printpara(p, pp);
-			pnode_print(p, pp);
-			pnode_unlink(pp);
-		}
-	}
+	pnode_printtitle(p, pn);
 	macro_argline(p, "Bl",
 	    pn->node == NODE_ORDEREDLIST ? "-enum" : "-bullet");
 	TAILQ_FOREACH(pp, &pn->childq, child) {
@@ -1209,6 +1218,7 @@ pnode_printlist(struct parse *p, struct 
 		pnode_print(p, pp);
 	}
 	macro_line(p, "El");
+	pnode_unlinksub(pn);
 }
 
 static void
@@ -1216,13 +1226,7 @@ pnode_printvariablelist(struct parse *p,
 {
 	struct pnode	*pp;
 
-	TAILQ_FOREACH(pp, &pn->childq, child) {
-		if (pp->node == NODE_TITLE) {
-			pnode_printpara(p, pp);
-			pnode_print(p, pp);
-			pnode_unlink(pp);
-		}
-	}
+	pnode_printtitle(p, pn);
 	macro_line(p, "Bl -tag -width Ds");
 	TAILQ_FOREACH(pp, &pn->childq, child) {
 		if (pp->node == NODE_VARLISTENTRY)
@@ -1231,6 +1235,7 @@ pnode_printvariablelist(struct parse *p,
 			macro_nodeline(p, "It", pp);
 	}
 	macro_line(p, "El");
+	pnode_unlinksub(pn);
 }
 
 /*
@@ -1262,7 +1267,6 @@ pnode_print(struct parse *p, struct pnod
 		return;
 	case NODE_ARG:
 		pnode_printarg(p, pn);
-		pnode_unlinksub(pn);
 		break;
 	case NODE_AUTHOR:
 		macro_open(p, "An");
@@ -1275,7 +1279,6 @@ pnode_print(struct parse *p, struct pnod
 		break;
 	case NODE_CITEREFENTRY:
 		pnode_printciterefentry(p, pn);
-		pnode_unlinksub(pn);
 		break;
 	case NODE_CITETITLE:
 		macro_open(p, "%T");
@@ -1311,7 +1314,6 @@ pnode_print(struct parse *p, struct pnod
 		break;
 	case NODE_FUNCPROTOTYPE:
 		pnode_printfuncprototype(p, pn);
-		pnode_unlinksub(pn);
 		break;
 	case NODE_FUNCSYNOPSISINFO:
 		macro_open(p, "Fd");
@@ -1328,11 +1330,9 @@ pnode_print(struct parse *p, struct pnod
 		break;
 	case NODE_ITEMIZEDLIST:
 		pnode_printlist(p, pn);
-		pnode_unlinksub(pn);
 		break;
 	case NODE_GROUP:
 		pnode_printgroup(p, pn);
-		pnode_unlinksub(pn);
 		break;
 	case NODE_KEYSYM:
 		macro_open(p, "Sy");
@@ -1355,7 +1355,6 @@ pnode_print(struct parse *p, struct pnod
 		break;
 	case NODE_MML_MFENCED:
 		pnode_printmathfenced(p, pn);
-		pnode_unlinksub(pn);
 		break;
 	case NODE_MML_MROW:
 	case NODE_MML_MI:
@@ -1369,14 +1368,12 @@ pnode_print(struct parse *p, struct pnod
 	case NODE_MML_MSUB:
 	case NODE_MML_MSUP:
 		pnode_printmath(p, pn);
-		pnode_unlinksub(pn);
 		break;
 	case NODE_OPTION:
 		macro_open(p, "Fl");
 		break;
 	case NODE_ORDEREDLIST:
 		pnode_printlist(p, pn);
-		pnode_unlinksub(pn);
 		break;
 	case NODE_PARA:
 		pnode_printpara(p, pn);
@@ -1417,7 +1414,6 @@ pnode_print(struct parse *p, struct pnod
 		break;
 	case NODE_REFSYNOPSISDIV:
 		pnode_printrefsynopsisdiv(p, pn);
-		macro_line(p, "Sh SYNOPSIS");
 		break;
 	case NODE_PREFACE:
 	case NODE_SECTION:
@@ -1442,7 +1438,6 @@ pnode_print(struct parse *p, struct pnod
 	case NODE_TABLE:
 	case NODE_INFORMALTABLE:
 		pnode_printtable(p, pn);
-		pnode_unlinksub(pn);
 		break;
 	case NODE_TEXT:
 		bufclear(p);
@@ -1501,11 +1496,9 @@ pnode_print(struct parse *p, struct pnod
 		break;
 	case NODE_VARIABLELIST:
 		pnode_printvariablelist(p, pn);
-		pnode_unlinksub(pn);
 		break;
 	case NODE_VARLISTENTRY:
 		pnode_printvarlistentry(p, pn);
-		pnode_unlinksub(pn);
 		break;
 	case NODE_VARNAME:
 		macro_open(p, "Va");
--
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