[Samba] The connection would be broken when read rate is too big

[Chenyehua]

Hi samba-team,
I met a problem recently:

Problem Description:
The connection would be broken when read rate is too big.

Environment:
Samba 4.3.11
Ubuntu server 14.04

Configuration:
usershare allow guests = yes
   max protocol = SMB3
   large readwrite = yes
   use sendfile = yes
   aio read size = 1024
   oplocks = yes
   deadtime = 10
   aio write behind = true
   clustering = yes
   store dos attributes = yes
   vfs objects = acl_xattr
   socket options = TCP_NODELAY SO_RCVBUF=131072 SO_SNDBUF=131072
   ctdbd socket = /var/run/ctdb/ctdbd.socket
   log level = 2
   security = user

I add some logs, found when the send queue is more than the max, it won’t allocate memory to the state->req in smbd_smb2_request_next_incoming function.
Then, the smbd_smb2_io_handler function mark the fd to not readable because state->req == NULL, and never mark it to readable again.
Then the Request Expiration Timer will break the connection.

I don’t know why the fd is marked to readable when the send queue is more than the max.
Or why mark the fd readable but not allocate memory to the state->req.

My solution:
Allocate memory to the state->req before return when the send queue is more than the max in smbd_smb2_request_next_incoming function.

Could you give us some help about the problem.

Br
Thanks.

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