[package] busybox: add 6RD prefix sanity checking as mandated by RFC5969, bump pkg revision

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@23990 3c298f89-4303-0410-b956-a3cf2f4a3e73

package/busybox/Makefile

@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=busybox
 PKG_VERSION:=1.17.3
-PKG_RELEASE:=1
+PKG_RELEASE:=2
 PKG_FLAGS:=essential
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.bz2

package/busybox/patches/244-udhcpc_add_6rd_option.patch

@@ -58,7 +58,7 @@
  /* really simple implementation, just count the bits */
  static int mton(uint32_t mask)
  {
-@@ -177,6 +195,60 @@ static NOINLINE char *xmalloc_optname_op
+@@ -177,6 +195,70 @@ static NOINLINE char *xmalloc_optname_op
  
  			return ret;
  		}
@@ -85,6 +85,15 @@
 +			 * We convert it to a string "IPv4MaskLen 6rdPrefixLen 6rdPrefix 6rdBRIPv4Address"
 +			 */
 +
++			/* Sanity check: ensure that our length is at least 22 bytes, that
++			 * IPv4MaskLen is <= 32, 6rdPrefixLen <= 128 and that the sum of
++			 * (32 - IPv4MaskLen) + 6rdPrefixLen is less than or equal to 128.
++			 * If any of these requirements is not fulfilled, return with empty
++			 * value.
++			 */
++			if ((len >= 22) && (*option <= 32) && (*(option+1) <= 128) &&
++			    (((32 - *option) + *(option+1)) <= 128))
++			{
 +				/* IPv4MaskLen */
 +				dest += sprintf(dest, "%u ", *option++);
 +				len--;
@@ -113,6 +122,7 @@
 +					 */
 +					break;
 +				}
++			}
 +
 +			return ret;
 +		}