linux/net/rxrpc/sysctl.c
David Howells 88e2215975 rxrpc: Fix listen() setting the bar too high for the prealloc rings
AF_RXRPC's listen() handler lets you set the backlog up to 32 (if you bump
up the sysctl), but whilst the preallocation circular buffers have 32 slots
in them, one of them has to be a dead slot because we're using CIRC_CNT().

This means that listen(rxrpc_sock, 32) will cause an oops when the socket
is closed because rxrpc_service_prealloc_one() allocated one too many calls
and rxrpc_discard_prealloc() won't then be able to get rid of them because
it'll think the ring is empty.  rxrpc_release_calls_on_socket() then tries
to abort them, but oopses because call->peer isn't yet set.

Fix this by setting the maximum backlog to RXRPC_BACKLOG_MAX - 1 to match
the ring capacity.

 BUG: kernel NULL pointer dereference, address: 0000000000000086
 ...
 RIP: 0010:rxrpc_send_abort_packet+0x73/0x240 [rxrpc]
 Call Trace:
  <TASK>
  ? __wake_up_common_lock+0x7a/0x90
  ? rxrpc_notify_socket+0x8e/0x140 [rxrpc]
  ? rxrpc_abort_call+0x4c/0x60 [rxrpc]
  rxrpc_release_calls_on_socket+0x107/0x1a0 [rxrpc]
  rxrpc_release+0xc9/0x1c0 [rxrpc]
  __sock_release+0x37/0xa0
  sock_close+0x11/0x20
  __fput+0x89/0x240
  task_work_run+0x59/0x90
  do_exit+0x319/0xaa0

Fixes: 00e907127e ("rxrpc: Preallocate peers, conns and calls for incoming service requests")
Reported-by: Marc Dionne <marc.dionne@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-afs@lists.infradead.org
Link: https://lists.infradead.org/pipermail/linux-afs/2022-March/005079.html
Signed-off-by: David S. Miller <davem@davemloft.net>
2022-05-22 21:30:53 +01:00

139 lines
3.6 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/* sysctls for configuring RxRPC operating parameters
*
* Copyright (C) 2014 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#include <linux/sysctl.h>
#include <net/sock.h>
#include <net/af_rxrpc.h>
#include "ar-internal.h"
static struct ctl_table_header *rxrpc_sysctl_reg_table;
static const unsigned int four = 4;
static const unsigned int max_backlog = RXRPC_BACKLOG_MAX - 1;
static const unsigned int n_65535 = 65535;
static const unsigned int n_max_acks = RXRPC_RXTX_BUFF_SIZE - 1;
static const unsigned long one_jiffy = 1;
static const unsigned long max_jiffies = MAX_JIFFY_OFFSET;
/*
* RxRPC operating parameters.
*
* See Documentation/networking/rxrpc.rst and the variable definitions for more
* information on the individual parameters.
*/
static struct ctl_table rxrpc_sysctl_table[] = {
/* Values measured in milliseconds but used in jiffies */
{
.procname = "req_ack_delay",
.data = &rxrpc_requested_ack_delay,
.maxlen = sizeof(unsigned long),
.mode = 0644,
.proc_handler = proc_doulongvec_ms_jiffies_minmax,
.extra1 = (void *)&one_jiffy,
.extra2 = (void *)&max_jiffies,
},
{
.procname = "soft_ack_delay",
.data = &rxrpc_soft_ack_delay,
.maxlen = sizeof(unsigned long),
.mode = 0644,
.proc_handler = proc_doulongvec_ms_jiffies_minmax,
.extra1 = (void *)&one_jiffy,
.extra2 = (void *)&max_jiffies,
},
{
.procname = "idle_ack_delay",
.data = &rxrpc_idle_ack_delay,
.maxlen = sizeof(unsigned long),
.mode = 0644,
.proc_handler = proc_doulongvec_ms_jiffies_minmax,
.extra1 = (void *)&one_jiffy,
.extra2 = (void *)&max_jiffies,
},
{
.procname = "idle_conn_expiry",
.data = &rxrpc_conn_idle_client_expiry,
.maxlen = sizeof(unsigned long),
.mode = 0644,
.proc_handler = proc_doulongvec_ms_jiffies_minmax,
.extra1 = (void *)&one_jiffy,
.extra2 = (void *)&max_jiffies,
},
{
.procname = "idle_conn_fast_expiry",
.data = &rxrpc_conn_idle_client_fast_expiry,
.maxlen = sizeof(unsigned long),
.mode = 0644,
.proc_handler = proc_doulongvec_ms_jiffies_minmax,
.extra1 = (void *)&one_jiffy,
.extra2 = (void *)&max_jiffies,
},
/* Non-time values */
{
.procname = "reap_client_conns",
.data = &rxrpc_reap_client_connections,
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = (void *)SYSCTL_ONE,
.extra2 = (void *)&n_65535,
},
{
.procname = "max_backlog",
.data = &rxrpc_max_backlog,
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = (void *)&four,
.extra2 = (void *)&max_backlog,
},
{
.procname = "rx_window_size",
.data = &rxrpc_rx_window_size,
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = (void *)SYSCTL_ONE,
.extra2 = (void *)&n_max_acks,
},
{
.procname = "rx_mtu",
.data = &rxrpc_rx_mtu,
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = (void *)SYSCTL_ONE,
.extra2 = (void *)&n_65535,
},
{
.procname = "rx_jumbo_max",
.data = &rxrpc_rx_jumbo_max,
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = (void *)SYSCTL_ONE,
.extra2 = (void *)&four,
},
{ }
};
int __init rxrpc_sysctl_init(void)
{
rxrpc_sysctl_reg_table = register_net_sysctl(&init_net, "net/rxrpc",
rxrpc_sysctl_table);
if (!rxrpc_sysctl_reg_table)
return -ENOMEM;
return 0;
}
void rxrpc_sysctl_exit(void)
{
if (rxrpc_sysctl_reg_table)
unregister_net_sysctl_table(rxrpc_sysctl_reg_table);
}