X-Git-Url: https://git.tcpdump.org/tcpdump/blobdiff_plain/e5b3ec43d30492803412cc76eba7ac2d1accba7d..c6d472bf63488b0c2ab7ab9f4b32c68dd2c8ea2b:/interface.h

diff --git a/interface.h b/interface.h
index 33ddb776..59c1eefd 100644
--- a/interface.h
+++ b/interface.h
@@ -104,9 +104,21 @@ extern int32_t thiszone;	/* seconds offset from gmt to local time */
  * that "snapend - (l)" underflows.
  *
  * The check is for <= rather than < because "l" might be 0.
+ *
+ * We cast the pointers to uintptr_t to make sure that the compiler
+ * doesn't optimize away any of these tests (which it is allowed to
+ * do, as adding an integer to, or subtracting an integer from, a
+ * pointer assumes that the pointer is a pointer to an element of an
+ * array and that the result of the addition or subtraction yields a
+ * pointer to another member of the array, so that, for example, if
+ * you subtract a positive integer from a pointer, the result is
+ * guaranteed to be less than the original pointer value). See
+ *
+ *	http://www.kb.cert.org/vuls/id/162289
  */
-#define TTEST2(var, l) (snapend - (l) <= snapend && \
-			(const u_char *)&(var) <= snapend - (l))
+#define TTEST2(var, l) \
+	((uintptr_t)snapend - (l) <= (uintptr_t)snapend && \
+	   (uintptr_t)&(var) <= (uintptr_t)snapend - (l))
 
 /* True if "var" was captured */
 #define TTEST(var) TTEST2(var, sizeof(var))