linux/net/rxrpc
David Howells d7e15835ab rxrpc: Kernel calls get stuck in recvmsg
Calls made through the in-kernel interface can end up getting stuck because
of a missed variable update in a loop in rxrpc_recvmsg_data().  The problem
is like this:

 (1) A new packet comes in and doesn't cause a notification to be given to
     the client as there's still another packet in the ring - the
     assumption being that if the client will keep drawing off data until
     the ring is empty.

 (2) The client is in rxrpc_recvmsg_data(), inside the big while loop that
     iterates through the packets.  This copies the window pointers into
     variables rather than using the information in the call struct
     because:

     (a) MSG_PEEK might be in effect;

     (b) we need a barrier after reading call->rx_top to pair with the
     	 barrier in the softirq routine that loads the buffer.

 (3) The reading of call->rx_top is done outside of the loop, and top is
     never updated whilst we're in the loop.  This means that even through
     there's a new packet available, we don't see it and may return -EFAULT
     to the caller - who will happily return to the scheduler and await the
     next notification.

 (4) No further notifications are forthcoming until there's an abort as the
     ring isn't empty.

The fix is to move the read of call->rx_top inside the loop - but it needs
to be done before the condition is checked.

Reported-by: Marc Dionne <marc.dionne@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Marc Dionne <marc.dionne@auristor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-02-26 21:30:12 -05:00
..
af_rxrpc.c rxrpc: Allow listen(sock, 0) to be used to disable listening 2017-01-09 11:10:02 +00:00
ar-internal.h rxrpc: Allow listen(sock, 0) to be used to disable listening 2017-01-09 11:10:02 +00:00
call_accept.c rxrpc: Allow listen(sock, 0) to be used to disable listening 2017-01-09 11:10:02 +00:00
call_event.c rxrpc: Need to produce an ACK for service op if op takes a long time 2016-10-06 08:11:50 +01:00
call_object.c rxrpc: Fix handling of enums-to-string translation in tracing 2017-01-05 10:38:33 +00:00
conn_client.c rxrpc: Fix handling of enums-to-string translation in tracing 2017-01-05 10:38:33 +00:00
conn_event.c rxrpc: The offset field in struct rxrpc_skb_priv is unnecessary 2016-09-30 14:39:28 +01:00
conn_object.c rxrpc: Add some more tracing 2017-01-05 11:39:12 +00:00
conn_service.c rxrpc: Add connection tracepoint and client conn state tracepoint 2016-09-17 11:24:03 +01:00
input.c rxrpc: Add some more tracing 2017-01-05 11:39:12 +00:00
insecure.c rxrpc: Rewrite the data and ack handling code 2016-09-08 11:10:12 +01:00
Kconfig rxrpc: Add config to inject packet loss 2016-09-17 11:24:04 +01:00
key.c rxrpc: Fix an assertion in rxrpc_read() 2017-02-24 11:42:55 -05:00
local_event.c rxrpc: The offset field in struct rxrpc_skb_priv is unnecessary 2016-09-30 14:39:28 +01:00
local_object.c rxrpc: Reduce the rxrpc_local::services list to a pointer 2016-09-29 22:57:47 +01:00
Makefile rxrpc: Change module filename to rxrpc.ko 2017-02-17 15:09:19 -05:00
misc.c rxrpc: Fix handling of enums-to-string translation in tracing 2017-01-05 10:38:33 +00:00
output.c rxrpc: Don't request an ACK on the last DATA packet of a call's Tx phase 2016-10-06 08:11:51 +01:00
peer_event.c rxrpc: Add per-peer RTT tracker 2016-09-22 01:26:25 +01:00
peer_object.c rxrpc: Fix checking of error from ip6_route_output() 2016-10-13 08:43:17 +01:00
proc.c rxrpc: Show a call's hard-ACK cursors in /proc/net/rxrpc_calls 2017-01-05 11:39:44 +00:00
recvmsg.c rxrpc: Kernel calls get stuck in recvmsg 2017-02-26 21:30:12 -05:00
rxkad.c rxrpc: Fix warning by splitting rxrpc_send_call_packet() 2016-10-06 08:11:49 +01:00
security.c rxrpc: Reduce the rxrpc_local::services list to a pointer 2016-09-29 22:57:47 +01:00
sendmsg.c scm: remove use CMSG{_COMPAT}_ALIGN(sizeof(struct {compat_}cmsghdr)) 2017-01-04 13:04:37 -05:00
skbuff.c rxrpc: Make Tx loss-injection go through normal return and adjust tracing 2016-09-29 22:37:15 +01:00
sysctl.c rxrpc: Keep the call timeouts as ktimes rather than jiffies 2016-09-30 14:40:11 +01:00
utils.c rxrpc: Make IPv6 support conditional on CONFIG_IPV6 2016-09-17 03:58:45 -04:00