cve/published/2022/CVE-2022-49838.mbox

From bippy-1.1.0 Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman <gregkh@kernel.org>
To: <linux-cve-announce@vger.kernel.org>
Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org>
Subject: CVE-2022-49838: sctp: clear out_curr if all frag chunks of current msg are pruned

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

sctp: clear out_curr if all frag chunks of current msg are pruned

A crash was reported by Zhen Chen:

  list_del corruption, ffffa035ddf01c18->next is NULL
  WARNING: CPU: 1 PID: 250682 at lib/list_debug.c:49 __list_del_entry_valid+0x59/0xe0
  RIP: 0010:__list_del_entry_valid+0x59/0xe0
  Call Trace:
   sctp_sched_dequeue_common+0x17/0x70 [sctp]
   sctp_sched_fcfs_dequeue+0x37/0x50 [sctp]
   sctp_outq_flush_data+0x85/0x360 [sctp]
   sctp_outq_uncork+0x77/0xa0 [sctp]
   sctp_cmd_interpreter.constprop.0+0x164/0x1450 [sctp]
   sctp_side_effects+0x37/0xe0 [sctp]
   sctp_do_sm+0xd0/0x230 [sctp]
   sctp_primitive_SEND+0x2f/0x40 [sctp]
   sctp_sendmsg_to_asoc+0x3fa/0x5c0 [sctp]
   sctp_sendmsg+0x3d5/0x440 [sctp]
   sock_sendmsg+0x5b/0x70

and in sctp_sched_fcfs_dequeue() it dequeued a chunk from stream
out_curr outq while this outq was empty.

Normally stream->out_curr must be set to NULL once all frag chunks of
current msg are dequeued, as we can see in sctp_sched_dequeue_done().
However, in sctp_prsctp_prune_unsent() as it is not a proper dequeue,
sctp_sched_dequeue_done() is not called to do this.

This patch is to fix it by simply setting out_curr to NULL when the
last frag chunk of current msg is dequeued from out_curr stream in
sctp_prsctp_prune_unsent().

The Linux kernel CVE team has assigned CVE-2022-49838 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 4.15 with commit 5bbbbe32a43199c2b9ea5ea66fab6241c64beb51 and fixed in 5.10.156 with commit e27458b18b35caee4b27b37a4a9c503b93cae5cc
	Issue introduced in 4.15 with commit 5bbbbe32a43199c2b9ea5ea66fab6241c64beb51 and fixed in 5.15.81 with commit 2ea600b598dd3e061854dd4dd5b4c815397dfcea
	Issue introduced in 4.15 with commit 5bbbbe32a43199c2b9ea5ea66fab6241c64beb51 and fixed in 6.0.10 with commit 3eff34e01062ec08fbb45ce2baaaa644550be821
	Issue introduced in 4.15 with commit 5bbbbe32a43199c2b9ea5ea66fab6241c64beb51 and fixed in 6.1 with commit 2f201ae14ae0f91dbf1cffea7bb1e29e81d4d108

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2022-49838
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	net/sctp/outqueue.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/e27458b18b35caee4b27b37a4a9c503b93cae5cc
	https://git.kernel.org/stable/c/2ea600b598dd3e061854dd4dd5b4c815397dfcea
	https://git.kernel.org/stable/c/3eff34e01062ec08fbb45ce2baaaa644550be821
	https://git.kernel.org/stable/c/2f201ae14ae0f91dbf1cffea7bb1e29e81d4d108