protocol/client: Fix negative return in client_setvolume

PROBLEM:
The function dict_serialized_length could, owing to an error,
return a negative integer (-EINVAL) that gets assigned to an
unsigned int member 'dict_len' of gf_setvolume_req structure.

FIX:
Hold the value returned by dict_serialized_length in local
variable ret (which is a signed int). Test if ret is negative,
in which case the control would anyway branch to the label fail
where the function returns. Otherwise dict_len is assigned with
ret, in turn giving a more meaningful value to the attribute
length.

TEST:
Attached gdb to glusterfs mount process, set breakpoint at
client_setvolume, forced dict_serialized_length to return
-EINVAL (indirectly by forcing _dict_serialized_length to return
-EINVAL after setting count to -1 within its body) and checked
the value of ret (which is now sure to contain a negative value)
whose value will be appropriately tested to decide the next
course of action within client_setvolume: whether to simply
exit due to an error or execute the subsequent statements.

Change-Id: Ib22ad8f30d8ae04acaf2ff5bfee9c348a2c47148
BUG: 789278
Signed-off-by: Krutika Dhananjay <kdhananj@redhat.com>
Reviewed-on: http://review.gluster.com/3755
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/xlators/protocol/client/src/client-handshake.c b/xlators/protocol/client/src/client-handshake.c
index 3242cf0aeb6..5c4816ee20a 100644
--- a/xlators/protocol/client/src/client-handshake.c
+++ b/xlators/protocol/client/src/client-handshake.c
@@ -1554,13 +1554,14 @@ client_setvolume (xlator_t *this, struct rpc_clnt *rpc)
                         client_get_lk_ver (conf));
         }
 
-        req.dict.dict_len = dict_serialized_length (options);
-        if (req.dict.dict_len < 0) {
+        ret = dict_serialized_length (options);
+        if (ret < 0) {
                 gf_log (this->name, GF_LOG_ERROR,
                         "failed to get serialized length of dict");
                 ret = -1;
                 goto fail;
         }
+        req.dict.dict_len = ret;
         req.dict.dict_val = GF_CALLOC (1, req.dict.dict_len,
                                        gf_client_mt_clnt_req_buf_t);
         ret = dict_serialize (options, req.dict.dict_val);