linux-cve-announce - CVE-2023-53742: kcsan: Avoid READ_ONCE() in read_instrumented

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [day] [month] [year] [list]
Message-ID: <2025120840-CVE-2023-53742-3a0d@gregkh>
Date: Mon,  8 Dec 2025 10:19:41 +0900
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2023-53742: kcsan: Avoid READ_ONCE() in read_instrumented_memory()

From: Greg Kroah-Hartman <gregkh@...nel.org>

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

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

kcsan: Avoid READ_ONCE() in read_instrumented_memory()

Haibo Li reported:

 | Unable to handle kernel paging request at virtual address
 |   ffffff802a0d8d7171
 | Mem abort info:o:
 |   ESR = 0x9600002121
 |   EC = 0x25: DABT (current EL), IL = 32 bitsts
 |   SET = 0, FnV = 0 0
 |   EA = 0, S1PTW = 0 0
 |   FSC = 0x21: alignment fault
 | Data abort info:o:
 |   ISV = 0, ISS = 0x0000002121
 |   CM = 0, WnR = 0 0
 | swapper pgtable: 4k pages, 39-bit VAs, pgdp=000000002835200000
 | [ffffff802a0d8d71] pgd=180000005fbf9003, p4d=180000005fbf9003,
 | pud=180000005fbf9003, pmd=180000005fbe8003, pte=006800002a0d8707
 | Internal error: Oops: 96000021 [#1] PREEMPT SMP
 | Modules linked in:
 | CPU: 2 PID: 45 Comm: kworker/u8:2 Not tainted
 |   5.15.78-android13-8-g63561175bbda-dirty #1
 | ...
 | pc : kcsan_setup_watchpoint+0x26c/0x6bc
 | lr : kcsan_setup_watchpoint+0x88/0x6bc
 | sp : ffffffc00ab4b7f0
 | x29: ffffffc00ab4b800 x28: ffffff80294fe588 x27: 0000000000000001
 | x26: 0000000000000019 x25: 0000000000000001 x24: ffffff80294fdb80
 | x23: 0000000000000000 x22: ffffffc00a70fb68 x21: ffffff802a0d8d71
 | x20: 0000000000000002 x19: 0000000000000000 x18: ffffffc00a9bd060
 | x17: 0000000000000001 x16: 0000000000000000 x15: ffffffc00a59f000
 | x14: 0000000000000001 x13: 0000000000000000 x12: ffffffc00a70faa0
 | x11: 00000000aaaaaaab x10: 0000000000000054 x9 : ffffffc00839adf8
 | x8 : ffffffc009b4cf00 x7 : 0000000000000000 x6 : 0000000000000007
 | x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffffffc00a70fb70
 | x2 : 0005ff802a0d8d71 x1 : 0000000000000000 x0 : 0000000000000000
 | Call trace:
 |  kcsan_setup_watchpoint+0x26c/0x6bc
 |  __tsan_read2+0x1f0/0x234
 |  inflate_fast+0x498/0x750
 |  zlib_inflate+0x1304/0x2384
 |  __gunzip+0x3a0/0x45c
 |  gunzip+0x20/0x30
 |  unpack_to_rootfs+0x2a8/0x3fc
 |  do_populate_rootfs+0xe8/0x11c
 |  async_run_entry_fn+0x58/0x1bc
 |  process_one_work+0x3ec/0x738
 |  worker_thread+0x4c4/0x838
 |  kthread+0x20c/0x258
 |  ret_from_fork+0x10/0x20
 | Code: b8bfc2a8 2a0803f7 14000007 d503249f (78bfc2a8) )
 | ---[ end trace 613a943cb0a572b6 ]-----

The reason for this is that on certain arm64 configuration since
e35123d83ee3 ("arm64: lto: Strengthen READ_ONCE() to acquire when
CONFIG_LTO=y"), READ_ONCE() may be promoted to a full atomic acquire
instruction which cannot be used on unaligned addresses.

Fix it by avoiding READ_ONCE() in read_instrumented_memory(), and simply
forcing the compiler to do the required access by casting to the
appropriate volatile type. In terms of generated code this currently
only affects architectures that do not use the default READ_ONCE()
implementation.

The only downside is that we are not guaranteed atomicity of the access
itself, although on most architectures a plain load up to machine word
size should still be atomic (a fact the default READ_ONCE() still relies
on itself).

The Linux kernel CVE team has assigned CVE-2023-53742 to this issue.


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

	Fixed in 6.1.28 with commit 706ae665747b629bcf87a2d7e6438602f904b8d5
	Fixed in 6.2.15 with commit 75c03a8cfc731519236f08c34c7e029ae153a613
	Fixed in 6.3.2 with commit f8f2297355513e5e0631e604ef9d7e449c7dcd00
	Fixed in 6.4 with commit 8dec88070d964bfeb4198f34cb5956d89dd1f557

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-2023-53742
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:
	kernel/kcsan/core.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/706ae665747b629bcf87a2d7e6438602f904b8d5
	https://git.kernel.org/stable/c/75c03a8cfc731519236f08c34c7e029ae153a613
	https://git.kernel.org/stable/c/f8f2297355513e5e0631e604ef9d7e449c7dcd00
	https://git.kernel.org/stable/c/8dec88070d964bfeb4198f34cb5956d89dd1f557