From: David Lamparter <equinox@opensourcerouting.org>
Date: Thu, 7 Sep 2017 12:54:42 +0000 (+0200)
Subject: bgpd: add safety check on ATTR_FLAG_BIT
X-Git-Tag: frr-4.0-dev~327^2~5
X-Git-Url: https://git.puffer.fish/?a=commitdiff_plain;h=96099b4030d374cf1d34b3a6f3fa0e2dc1ed7a99;p=matthieu%2Ffrr.git

bgpd: add safety check on ATTR_FLAG_BIT

Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
---

diff --git a/bgpd/bgp_attr.h b/bgpd/bgp_attr.h
index 4dd38459f8..ea1e736520 100644
--- a/bgpd/bgp_attr.h
+++ b/bgpd/bgp_attr.h
@@ -207,7 +207,12 @@ struct transit {
 	u_char *val;
 };
 
-#define ATTR_FLAG_BIT(X)  (1ULL << ((X) - 1))
+/* "(void) 0" will generate a compiler error.  this is a safety check to
+ * ensure we're not using a value that exceeds the bit size of attr->flag. */
+#define ATTR_FLAG_BIT(X) \
+	__builtin_choose_expr((X) >= 1 && (X) <= 64, \
+			      1ULL << ((X) - 1), \
+			      (void) 0)
 
 #define BGP_CLUSTER_LIST_LENGTH(attr)                                          \
 	(((attr)->flag & ATTR_FLAG_BIT(BGP_ATTR_CLUSTER_LIST))                 \