Commit be504be1 authored by David Howells's avatar David Howells Committed by Gu Bowen
Browse files

rxrpc: Fix listen() setting the bar too high for the prealloc rings 

stable inclusion
from stable-v4.19.247
commit 4a3a78b7918bdd723d8c7c9786522ca969bffcc4
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/IBP2XB
CVE: CVE-2022-49450

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4a3a78b7918bdd723d8c7c9786522ca969bffcc4



--------------------------------

[ Upstream commit 88e22159 ]

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: 00e90712 ("rxrpc: Preallocate peers, conns and calls for incoming service requests")
Reported-by: default avatarMarc Dionne <marc.dionne@auristor.com>
Signed-off-by: default avatarDavid 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: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
Signed-off-by: default avatarGu Bowen <gubowen5@huawei.com>
parent 16bceab9

net/rxrpc/sysctl.c

+2 −2
Original line number Diff line number Diff line
@@ -17,7 +17,7 @@ 
static struct ctl_table_header *rxrpc_sysctl_reg_table;

static const unsigned int one = 1;

static const unsigned int four = 4;

static const unsigned int thirtytwo = 32;

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;
@@ -111,7 +111,7 @@ static struct ctl_table rxrpc_sysctl_table[] = { 
		.mode		= 0644,

		.proc_handler	= proc_dointvec_minmax,

		.extra1		= (void *)&four,

		.extra2		= (void *)&thirtytwo,

		.extra2		= (void *)&max_backlog,

	},

	{

		.procname	= "rx_window_size",