ofp-print: Fix misaligned data access in ofp_print_error_msg().

The body of an OpenFlow error message often contains an inner OpenFlow
message, and when it does, the inner message starts at an odd multiple of 4
bytes from the beginning of the outer message.  That means that, on RISC
systems, accessing the inner message directly causes a bus error.  This
commit fixes the problem in a way that should make it difficult to recur.

This fixes the failure of tests 643, 645, and 651 on sparc seen here:
https://buildd.debian.org/status/fetch.php?pkg=openvswitch&arch=sparc&ver=2.1.0%2Bgit20140325-1&stamp=1396438624

Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Jarno Rajahalme <jrajahalme@nicira.com>

diff --git a/lib/ofp-errors.c b/lib/ofp-errors.c
index 30a021b..b53334c 100644 (file)
--- a/lib/ofp-errors.c
+++ b/lib/ofp-errors.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2013 Nicira, Inc.
+ * Copyright (c) 2012, 2013, 2014 Nicira, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -270,8 +270,10 @@ ofperr_get_code(enum ofperr error, enum ofp_version version)
 /* Tries to decode 'oh', which should be an OpenFlow OFPT_ERROR message.
  * Returns an OFPERR_* constant on success, 0 on failure.
  *
- * If 'payload' is nonnull, on success '*payload' is initialized to the
- * error's payload, and on failure it is cleared. */
+ * If 'payload' is nonnull, on success '*payload' is initialized with a copy of
+ * the error's payload (copying is required because the payload is not properly
+ * aligned).  The caller must free the payload (with ofpbuf_uninit()) when it
+ * is no longer needed.  On failure, '*payload' is cleared. */
 enum ofperr
 ofperr_decode_msg(const struct ofp_header *oh, struct ofpbuf *payload)
 {
@@ -321,7 +323,8 @@ ofperr_decode_msg(const struct ofp_header *oh, struct ofpbuf *payload)
     /* Translate the error type and code into an ofperr. */
     error = ofperr_decode(oh->version, vendor, type, code);
     if (error && payload) {
-        ofpbuf_use_const(payload, b.data, b.size);
+        ofpbuf_init(payload, b.size);
+        ofpbuf_push(payload, b.data, b.size);
     }
     return error;
 }

diff --git a/lib/ofp-print.c b/lib/ofp-print.c
index 4e57f9e..e14bd6e 100644 (file)
--- a/lib/ofp-print.c
+++ b/lib/ofp-print.c
@@ -1366,6 +1366,7 @@ ofp_print_error_msg(struct ds *string, const struct ofp_header *oh)
         ds_put_cstr(string, s);
         free(s);
     }
+    ofpbuf_uninit(&payload);
 }
 
 static void