Import a vendor fix for a list overrun.

This has been considered as a security hole on some specialized ml,
but currently the secteam@ doesn't consider that way.

Reviewed by:	emaste, des
Sponsored by:	Sandvine Incorporated
MFC after:	3 days

2 files changed, 13 insertions, 7 deletions

diff --git a/contrib/gdtoa/gdtoaimp.h b/contrib/gdtoa/gdtoaimp.h
index c550ada..9991ffa 100644
--- a/contrib/gdtoa/gdtoaimp.h
+++ b/contrib/gdtoa/gdtoaimp.h
@@ -485,7 +485,7 @@ extern pthread_mutex_t __gdtoa_locks[2];
 		_pthread_mutex_unlock(&__gdtoa_locks[n]);	\
 } while(0)
 
-#define Kmax 15
+#define Kmax 9
 
  struct
 Bigint {
diff --git a/contrib/gdtoa/misc.c b/contrib/gdtoa/misc.c
index b3ce7c9..8d2888e 100644
--- a/contrib/gdtoa/misc.c
+++ b/contrib/gdtoa/misc.c
@@ -55,7 +55,9 @@ Balloc
 #endif
 
 	ACQUIRE_DTOA_LOCK(0);
-	if ( (rv = freelist[k]) !=0) {
+	/* The k > Kmax case does not need ACQUIRE_DTOA_LOCK(0), */
+	/* but this case seems very unlikely. */
+	if (k <= Kmax && (rv = freelist[k]) !=0) {
 		freelist[k] = rv->next;
 		}
 	else {
@@ -65,7 +67,7 @@ Balloc
 #else
 		len = (sizeof(Bigint) + (x-1)*sizeof(ULong) + sizeof(double) - 1)
 			/sizeof(double);
-		if (pmem_next - private_mem + len <= PRIVATE_mem) {
+		if (k <= Kmax && pmem_next - private_mem + len <= PRIVATE_mem) {
 			rv = (Bigint*)pmem_next;
 			pmem_next += len;
 			}
@@ -89,10 +91,14 @@ Bfree
 #endif
 {
 	if (v) {
-		ACQUIRE_DTOA_LOCK(0);
-		v->next = freelist[v->k];
-		freelist[v->k] = v;
-		FREE_DTOA_LOCK(0);
+		if (v->k > Kmax)
+			free((void*)v);
+		else {
+			ACQUIRE_DTOA_LOCK(0);
+			v->next = freelist[v->k];
+			freelist[v->k] = v;
+			FREE_DTOA_LOCK(0);
+			}
 		}
 	}