From: Ben Pfaff <blp@nicira.com>
Date: Thu, 19 Jul 2012 07:15:19 +0000 (-0700)
Subject: nx-match: Succeed pulling 0-byte nx-match from NULL buffer.
X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?p=openvswitch;a=commitdiff_plain;h=a3a0c29e2b11d8fcae86043cd16520ecbaa03731

nx-match: Succeed pulling 0-byte nx-match from NULL buffer.

I don't think this corner case can come up in a real OpenFlow message,
because the presence of the OpenFlow header guarantees that the ofpbuf's
data is nonnull, but it did in a simple test that is coming up in a few
commits.

Signed-off-by: Ben Pfaff <blp@nicira.com>
---

diff --git a/lib/nx-match.c b/lib/nx-match.c
index 3e3b4c69..8b2a8229 100644
--- a/lib/nx-match.c
+++ b/lib/nx-match.c
@@ -99,6 +99,14 @@ nx_pull_match__(struct ofpbuf *b, unsigned int match_len, bool strict,
 
     assert((cookie != NULL) == (cookie_mask != NULL));
 
+    cls_rule_init_catchall(rule, priority);
+    if (cookie) {
+        *cookie = *cookie_mask = htonll(0);
+    }
+    if (!match_len) {
+        return 0;
+    }
+
     p = ofpbuf_try_pull(b, ROUND_UP(match_len, 8));
     if (!p) {
         VLOG_DBG_RL(&rl, "nx_match length %u, rounded up to a "
@@ -107,10 +115,6 @@ nx_pull_match__(struct ofpbuf *b, unsigned int match_len, bool strict,
         return OFPERR_OFPBMC_BAD_LEN;
     }
 
-    cls_rule_init_catchall(rule, priority);
-    if (cookie) {
-        *cookie = *cookie_mask = htonll(0);
-    }
     for (;
          (header = nx_entry_ok(p, match_len)) != 0;
          p += 4 + NXM_LENGTH(header), match_len -= 4 + NXM_LENGTH(header)) {