vppinfra: fix cpu flag string overflow

Type: fix

Change-Id: Idb1fff8a172034044bb33d5b271a84d1fd672ef5
Signed-off-by: Benoît Ganne <bganne@cisco.com>
diff --git a/src/vppinfra/cpu.c b/src/vppinfra/cpu.c
index c1ff7dd..2da87d1 100644
--- a/src/vppinfra/cpu.c
+++ b/src/vppinfra/cpu.c
@@ -183,12 +183,10 @@
 
 
 static inline char const *
-flag_skip_prefix (char const *flag)
+flag_skip_prefix (char const *flag, const char *pfx, int len)
 {
-  if (memcmp (flag, "x86_", sizeof ("x86_") - 1) == 0)
-    return flag + sizeof ("x86_") - 1;
-  if (memcmp (flag, "aarch64_", sizeof ("aarch64_") - 1) == 0)
-    return flag + sizeof ("aarch64_") - 1;
+  if (0 == strncmp (flag, pfx, len - 1))
+    return flag + len - 1;
   return flag;
 }
 
@@ -198,13 +196,13 @@
 #if defined(__x86_64__)
 #define _(flag, func, reg, bit) \
   if (clib_cpu_supports_ ## flag()) \
-    s = format (s, "%s ", flag_skip_prefix(#flag));
+    s = format (s, "%s ", flag_skip_prefix(#flag, "x86_", sizeof("x86_")));
   foreach_x86_64_flags return s;
 #undef _
 #elif defined(__aarch64__)
 #define _(flag, bit) \
   if (clib_cpu_supports_ ## flag()) \
-    s = format (s, "%s ", flag_skip_prefix(#flag));
+    s = format (s, "%s ", flag_skip_prefix(#flag, "aarch64_", sizeof("aarch64_")));
   foreach_aarch64_flags return s;
 #undef _
 #else /* ! ! __x86_64__ && ! __aarch64__ */