[ovs-dev] [PATCH v1] Fix crash when processing malformed Bundle Add message in OVS

[Anju Thomas]

Hi Ben,

Yes. This patch certainly looks more cleaner and better to me .

Thanks
Anju
 -----Original Message-----
From: Ben Pfaff [mailto:blp at ovn.org] 
Sent: Thursday, May 10, 2018 2:33 AM
To: Anju Thomas <anju.thomas at ericsson.com>
Cc: dev at openvswitch.org
Subject: Re: [ovs-dev] [PATCH v1] Fix crash when processing malformed Bundle Add message in OVS

On Mon, May 07, 2018 at 10:58:06PM +0530, Anju Thomas wrote:
> When an OpenFlow Bundle Add message is received, a bundle entry is 
> created and the OpenFlow message embedded in the bundle add message is 
> processed.  If any error is encountered while processing the embedded 
> message, the bundle entry is freed. The bundle entry free function 
> assumes that the entry has been populated with a properly formatted 
> OpenFlow message and performs some message specific cleanup actions .
> This assumption does not hold true in the error case and OVS crashes 
> when performing the cleanup.
> 
> The fix is in case of errors, simply free the bundle entry without 
> attempting to perform any embedded message cleanup
> 
> Signed-off-by: Anju Thomas <anju.thomas at ericsson.com>

Thanks for the fix.

It's not really nice to have multiple levels of initialized-ness.  What do you think of this fix instead?

Thanks,

Ben.

--8<--------------------------cut here-------------------------->8--

From: Anju Thomas <anju.thomas at ericsson.com>
Date: Mon, 7 May 2018 22:58:06 +0530
Subject: [PATCH] Fix crash when processing malformed Bundle Add message in OVS

When an OpenFlow Bundle Add message is received, a bundle entry is created and the OpenFlow message embedded in the bundle add message is processed.  If any error is encountered while processing the embedded message, the bundle entry is freed. The bundle entry free function assumes that the entry has been populated with a properly formatted OpenFlow message and performs some message specific cleanup actions .
This assumption does not hold true in the error case and OVS crashes when performing the cleanup.

The fix is in case of errors, simply free the bundle entry without attempting to perform any embedded message cleanup

Signed-off-by: Anju Thomas <anju.thomas at ericsson.com>
Signed-off-by: Ben Pfaff <blp at ovn.org>
---
 ofproto/bundles.h | 13 -------------
 ofproto/ofproto.c | 21 +++++++++++++--------
 2 files changed, 13 insertions(+), 21 deletions(-)

diff --git a/ofproto/bundles.h b/ofproto/bundles.h index 806e853d6883..1164fddd8702 100644
--- a/ofproto/bundles.h
+++ b/ofproto/bundles.h
@@ -58,8 +58,6 @@ struct ofp_bundle {
     struct ovs_list   msg_list;  /* List of 'struct bundle_message's */
 };
 
-static inline struct ofp_bundle_entry *ofp_bundle_entry_alloc(
-    enum ofptype type, const struct ofp_header *oh);
 static inline void ofp_bundle_entry_free(struct ofp_bundle_entry *);
 
 enum ofperr ofp_bundle_open(struct ofconn *, uint32_t id, uint16_t flags, @@ -72,17 +70,6 @@ enum ofperr ofp_bundle_add_message(struct ofconn *, uint32_t id,
 
 void ofp_bundle_remove__(struct ofconn *, struct ofp_bundle *);
 

-static inline struct ofp_bundle_entry * -ofp_bundle_entry_alloc(enum ofptype type, const struct ofp_header *oh) -{
-    struct ofp_bundle_entry *entry = xmalloc(sizeof *entry);
-
-    entry->type = type;
-    entry->msg = xmemdup(oh, ntohs(oh->length));
-
-    return entry;
-}
-
 static inline void
 ofp_bundle_entry_free(struct ofp_bundle_entry *entry)  { diff --git a/ofproto/ofproto.c b/ofproto/ofproto.c index 36f4c0b16d48..565a45db1507 100644
--- a/ofproto/ofproto.c
+++ b/ofproto/ofproto.c
@@ -7899,7 +7899,6 @@ handle_bundle_add(struct ofconn *ofconn, const struct ofp_header *oh)
     struct ofproto *ofproto = ofconn_get_ofproto(ofconn);
     enum ofperr error;
     struct ofputil_bundle_add_msg badd;
-    struct ofp_bundle_entry *bmsg;
     enum ofptype type;
 
     error = reject_slave_controller(ofconn); @@ -7912,7 +7911,8 @@ handle_bundle_add(struct ofconn *ofconn, const struct ofp_header *oh)
         return error;
     }
 
-    bmsg = ofp_bundle_entry_alloc(type, badd.msg);
+    /* Allocate bundle entry and decode the embedded message. */
+    struct ofp_bundle_entry *bmsg = xmalloc(sizeof *bmsg);
 
     struct ofpbuf ofpacts;
     uint64_t ofpacts_stub[1024 / 8];
@@ -7951,18 +7951,23 @@ handle_bundle_add(struct ofconn *ofconn, const struct ofp_header *oh)
     } else {
         OVS_NOT_REACHED();
     }
-
     ofpbuf_uninit(&ofpacts);
-
-    if (!error) {
-        error = ofp_bundle_add_message(ofconn, badd.bundle_id, badd.flags,
-                                       bmsg, oh);
+    if (error) {
+        free(bmsg);
+        return error;
     }
 
+    /* Now that the embedded message has been successfully decoded, finish up
+     * initializing the bundle entry. */
+    bmsg->type = type;
+    bmsg->msg = xmemdup(oh, ntohs(oh->length));
+
+    /* Add bundle entry to bundle. */
+    error = ofp_bundle_add_message(ofconn, badd.bundle_id, badd.flags,
+                                   bmsg, oh);
     if (error) {
         ofp_bundle_entry_free(bmsg);
     }
-
     return error;
 }
 
--
2.16.1