compound fops: Fix file corruption issue

        Backport of: http://review.gluster.org/#/c/15654/

1. Address of a local variable @args is copied into state->req
in server3_3_compound (). But even after the function has gone out of
scope, in server_compound_resume () this pointer is accessed and
dereferenced. This patch fixes that.

2. Compound fops, by virtue of NOT having a vector sizer (like the one
writev has), ends up having both the header and the data (in case one of
its member fops is WRITEV) in the same hdr_iobuf. This buffer was not
being preserved through the lifetime of the compound fop, causing it to
be overwritten by a parallel write fop, even when the writev associated
with the currently executing compound fop is yet to hit the desk, thereby
corrupting the file's data. This is fixed by associating the hdr_iobuf with
the iobref so its memory remains valid through the lifetime of the fop.

3. Also fixed a use-after-free bug in protocol/client in compound fops cbk,
missed by Linux but caught by NetBSD.

Finally, big thanks to Pranith Kumar K and Raghavendra Gowdappa for their
help in debugging this file corruption issue.

Change-Id: I58da39ae544ad81192849926399a971c4c01c986
BUG: 1387984
Signed-off-by: Krutika Dhananjay <kdhananj@redhat.com>
Reviewed-on: http://review.gluster.org/15709
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
Reviewed-by: Raghavendra G <rgowdapp@redhat.com>
Smoke: Gluster Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>

4 files changed, 1 insertions, 15 deletions

diff --git a/rpc/rpc-lib/src/rpc-transport.c b/rpc/rpc-lib/src/rpc-transport.c
index 005b68c5cbc..6ee5e15ede4 100644
--- a/rpc/rpc-lib/src/rpc-transport.c
+++ b/rpc/rpc-lib/src/rpc-transport.c
@@ -123,10 +123,6 @@ rpc_transport_pollin_destroy (rpc_transport_pollin_t *pollin)
                 iobref_unref (pollin->iobref);
         }
 
-        if (pollin->hdr_iobuf) {
-                iobuf_unref (pollin->hdr_iobuf);
-        }
-
         if (pollin->private) {
                 /* */
                 GF_FREE (pollin->private);
@@ -158,7 +154,7 @@ rpc_transport_pollin_alloc (rpc_transport_t *this, struct iovec *vector,
         msg->iobref = iobref_ref (iobref);
         msg->private = private;
         if (hdr_iobuf)
-                msg->hdr_iobuf = iobuf_ref (hdr_iobuf);
+                iobref_add (iobref, hdr_iobuf);
 
 out:
         return msg;
diff --git a/rpc/rpc-lib/src/rpc-transport.h b/rpc/rpc-lib/src/rpc-transport.h
index f0add065065..4e7a8c46fae 100644
--- a/rpc/rpc-lib/src/rpc-transport.h
+++ b/rpc/rpc-lib/src/rpc-transport.h
@@ -163,7 +163,6 @@ struct rpc_transport_pollin {
         char vectored;
         void *private;
         struct iobref *iobref;
-        struct iobuf  *hdr_iobuf;
         char is_reply;
 };
 typedef struct rpc_transport_pollin rpc_transport_pollin_t;
diff --git a/rpc/rpc-lib/src/rpcsvc.c b/rpc/rpc-lib/src/rpcsvc.c
index f07e745a4b3..c792909cb87 100644
--- a/rpc/rpc-lib/src/rpcsvc.c
+++ b/rpc/rpc-lib/src/rpcsvc.c
@@ -373,9 +373,6 @@ rpcsvc_request_destroy (rpcsvc_request_t *req)
                 iobref_unref (req->iobref);
         }
 
-        if (req->hdr_iobuf)
-                iobuf_unref (req->hdr_iobuf);
-
         /* This marks the "end" of an RPC request. Reply is
            completely written to the socket and is on the way
            to the client. It is time to decrement the
@@ -690,9 +687,6 @@ rpcsvc_handle_rpc_call (rpcsvc_t *svc, rpc_transport_t *trans,
                 }
 
                 if (req->synctask) {
-                        if (msg->hdr_iobuf)
-                                req->hdr_iobuf = iobuf_ref (msg->hdr_iobuf);
-
                         ret = synctask_new (THIS->ctx->env,
                                             (synctask_fn_t) actor_fn,
                                             rpcsvc_check_and_reply_error, NULL,
diff --git a/rpc/rpc-lib/src/rpcsvc.h b/rpc/rpc-lib/src/rpcsvc.h
index 02e467e68a7..63a6dad8c2f 100644
--- a/rpc/rpc-lib/src/rpcsvc.h
+++ b/rpc/rpc-lib/src/rpcsvc.h
@@ -244,9 +244,6 @@ struct rpcsvc_request {
         /* Container for transport to store request-specific item */
         void                    *trans_private;
 
-        /* we need to ref the 'iobuf' in case of 'synctasking' it */
-        struct iobuf            *hdr_iobuf;
-
         /* pointer to cached reply for use in DRC */
         drc_cached_op_t         *reply;
 };