linux-cve-announce - CVE-2022-49450: rxrpc: Fix listen() setting the bar too high for the prealloc rings

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Message-ID: <2025022659-CVE-2022-49450-a2f7@gregkh>
Date: Wed, 26 Feb 2025 03:12:04 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2022-49450: rxrpc: Fix listen() setting the bar too high for the prealloc rings

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

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

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

The Linux kernel CVE team has assigned CVE-2022-49450 to this issue.


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

	Issue introduced in 4.9 with commit 00e907127e6f86d0f9b122d9b4347a8aa09a8b61 and fixed in 4.9.318 with commit 61fb38cfbb1d54d3dafd0c25752f684b3cd00b32
	Issue introduced in 4.9 with commit 00e907127e6f86d0f9b122d9b4347a8aa09a8b61 and fixed in 4.14.283 with commit 616f76498d5ddf26b997caf64a95cda3c8a55533
	Issue introduced in 4.9 with commit 00e907127e6f86d0f9b122d9b4347a8aa09a8b61 and fixed in 4.19.247 with commit 4a3a78b7918bdd723d8c7c9786522ca969bffcc4
	Issue introduced in 4.9 with commit 00e907127e6f86d0f9b122d9b4347a8aa09a8b61 and fixed in 5.4.198 with commit 91b34bf0409f43bb60453bab23c5beadd726d022
	Issue introduced in 4.9 with commit 00e907127e6f86d0f9b122d9b4347a8aa09a8b61 and fixed in 5.10.121 with commit 5b4826657d36c218e9f08e8d3223b0edce3de88f
	Issue introduced in 4.9 with commit 00e907127e6f86d0f9b122d9b4347a8aa09a8b61 and fixed in 5.15.46 with commit b3a9b227d5e7467b8518160ff034ea22bb9de573
	Issue introduced in 4.9 with commit 00e907127e6f86d0f9b122d9b4347a8aa09a8b61 and fixed in 5.17.14 with commit 369de57492c4f1a42563c5a3bd365822ca3bfc79
	Issue introduced in 4.9 with commit 00e907127e6f86d0f9b122d9b4347a8aa09a8b61 and fixed in 5.18.3 with commit e198f1930050e3115c80b67d9249f80f98a27c67
	Issue introduced in 4.9 with commit 00e907127e6f86d0f9b122d9b4347a8aa09a8b61 and fixed in 5.19 with commit 88e22159750b0d55793302eeed8ee603f5c1a95c

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-2022-49450
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/rxrpc/sysctl.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/61fb38cfbb1d54d3dafd0c25752f684b3cd00b32
	https://git.kernel.org/stable/c/616f76498d5ddf26b997caf64a95cda3c8a55533
	https://git.kernel.org/stable/c/4a3a78b7918bdd723d8c7c9786522ca969bffcc4
	https://git.kernel.org/stable/c/91b34bf0409f43bb60453bab23c5beadd726d022
	https://git.kernel.org/stable/c/5b4826657d36c218e9f08e8d3223b0edce3de88f
	https://git.kernel.org/stable/c/b3a9b227d5e7467b8518160ff034ea22bb9de573
	https://git.kernel.org/stable/c/369de57492c4f1a42563c5a3bd365822ca3bfc79
	https://git.kernel.org/stable/c/e198f1930050e3115c80b67d9249f80f98a27c67
	https://git.kernel.org/stable/c/88e22159750b0d55793302eeed8ee603f5c1a95c