commit 541cb790e1e6ce666c4deb6ebac3212f1bc8f289
Author: Eric Paris <eparis@redhat.com>
Date:   Tue Jan 8 11:42:21 2013 -0500

    start fixing stuff

diff --git a/libsepol/src/services.c b/libsepol/src/services.c
index 9b42d8d..23cef4c 100644
--- a/libsepol/src/services.c
+++ b/libsepol/src/services.c
@@ -47,7 +47,6 @@
 #define REASON_BUF_SIZE 30000
 /* The maximum size of each malloc'd expression buffer */
 #define EXPR_BUF_SIZE 1000
-/* Number expressions in a constraint - max seen in MLS policy is 21 */
 #define EXPR_BUFFERS 30
 
 #include <stdlib.h>
@@ -79,27 +78,42 @@ static sidtab_t mysidtab, *sidtab = &mysidtab;
 static policydb_t mypolicydb, *policydb = &mypolicydb;
 
 /* Stack services for RPN to infix conversion. Size is num of expr bufs */
-char *stack[EXPR_BUFFERS];
-int tos = 0;
- 
-void push(char * expr_ptr)
+static char **stack;
+static int stack_len;
+static int next_stack_entry;
+
+static void push(char * expr_ptr)
 {
-	if (tos >= EXPR_BUFFERS) {
-		ERR(NULL, "Stack is full");
-		return;
+	if (next_stack_entry >= stack_len) {
+		char **new_stack = stack;
+		int new_stack_len;
+
+		if (stack_len == 0)
+			new_stack_len = 32;
+		else
+			new_stack_len = stack_len * 2;
+
+		new_stack = realloc(stack, new_stack_len * sizeof(*stack));
+		if (!new_stack) {
+			ERR(NULL, "unable to allocate space");
+			return;
+		}
+		stack_len = new_stack_len;
+		stack = new_stack;
 	}
-	stack[tos] = expr_ptr;
-	tos++;
+	stack[next_stack_entry] = expr_ptr;
+	next_stack_entry++;
 }
- 
-char *pop()
+
+static char *pop(void)
 {
-	tos--;
-	if (tos < 0) {
-		ERR(NULL, "Stack is Empty");
+	next_stack_entry--;
+	if (next_stack_entry < 0) {
+		next_stack_entry = 0;
+		ERR(NULL, "pop called with no stack entries");
 		return NULL;
 	}
-	return (char *)stack[tos];
+	return stack[next_stack_entry];
 }
 /* End Stack services */
 
@@ -322,6 +336,10 @@ static int constraint_expr_eval_reason(context_struct_t * scontext,
 
 	/* Original function but with buffer support */
 	for (e = constraint->expr; e; e = e->next) {
+		if (expr_counter >= EXPR_BUFFERS) {
+			ERR(NULL, "%s: expr_buf overflow", __func__);
+			return -ENOMEM;
+		}
 		/* malloc a buffer to store each expression text component */
 		expr_buf[expr_counter] = malloc(EXPR_BUF_SIZE);
 		if (!expr_buf[expr_counter]) {
@@ -622,6 +640,10 @@ static int constraint_expr_eval_reason(context_struct_t * scontext,
 	for (x = 0; expr_buf[x] != NULL; x++) {
 		if (strncmp(expr_buf[x], "and", 3) == 0 || strncmp(expr_buf[x],
 					"or", 2) == 0) {
+			if (answer_counter >= EXPR_BUFFERS) {
+				ERR(NULL, "%s: answer_buf overflow", __func__);
+				return -ENOMEM;
+			}
 			b = pop();
 			b_len = strlen(b);
 			a = pop();