linux-cve-announce - CVE-2023-53217: nubus: Partially revert proc_create_single

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Message-ID: <2025091512-CVE-2023-53217-0de0@gregkh>
Date: Mon, 15 Sep 2025 16:21:51 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2023-53217: nubus: Partially revert proc_create_single_data() conversion

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

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

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

nubus: Partially revert proc_create_single_data() conversion

The conversion to proc_create_single_data() introduced a regression
whereby reading a file in /proc/bus/nubus results in a seg fault:

    # grep -r . /proc/bus/nubus/e/
    Data read fault at 0x00000020 in Super Data (pc=0x1074c2)
    BAD KERNEL BUSERR
    Oops: 00000000
    Modules linked in:
    PC: [<001074c2>] PDE_DATA+0xc/0x16
    SR: 2010  SP: 38284958  a2: 01152370
    d0: 00000001    d1: 01013000    d2: 01002790    d3: 00000000
    d4: 00000001    d5: 0008ce2e    a0: 00000000    a1: 00222a40
    Process grep (pid: 45, task=142f8727)
    Frame format=B ssw=074d isc=2008 isb=4e5e daddr=00000020 dobuf=01199e70
    baddr=001074c8 dibuf=ffffffff ver=f
    Stack from 01199e48:
	    01199e70 00222a58 01002790 00000000 011a3000 01199eb0 015000c0 00000000
	    00000000 01199ec0 01199ec0 000d551a 011a3000 00000001 00000000 00018000
	    d003f000 00000003 00000001 0002800d 01052840 01199fa8 c01f8000 00000000
	    00000029 0b532b80 00000000 00000000 00000029 0b532b80 01199ee4 00103640
	    011198c0 d003f000 00018000 01199fa8 00000000 011198c0 00000000 01199f4c
	    000b3344 011198c0 d003f000 00018000 01199fa8 00000000 00018000 011198c0
    Call Trace: [<00222a58>] nubus_proc_rsrc_show+0x18/0xa0
     [<000d551a>] seq_read+0xc4/0x510
     [<00018000>] fp_fcos+0x2/0x82
     [<0002800d>] __sys_setreuid+0x115/0x1c6
     [<00103640>] proc_reg_read+0x5c/0xb0
     [<00018000>] fp_fcos+0x2/0x82
     [<000b3344>] __vfs_read+0x2c/0x13c
     [<00018000>] fp_fcos+0x2/0x82
     [<00018000>] fp_fcos+0x2/0x82
     [<000b8aa2>] sys_statx+0x60/0x7e
     [<000b34b6>] vfs_read+0x62/0x12a
     [<00018000>] fp_fcos+0x2/0x82
     [<00018000>] fp_fcos+0x2/0x82
     [<000b39c2>] ksys_read+0x48/0xbe
     [<00018000>] fp_fcos+0x2/0x82
     [<000b3a4e>] sys_read+0x16/0x1a
     [<00018000>] fp_fcos+0x2/0x82
     [<00002b84>] syscall+0x8/0xc
     [<00018000>] fp_fcos+0x2/0x82
     [<0000c016>] not_ext+0xa/0x18
    Code: 4e5e 4e75 4e56 0000 206e 0008 2068 ffe8 <2068> 0020 2008 4e5e 4e75 4e56 0000 2f0b 206e 0008 2068 0004 2668 0020 206b ffe8
    Disabling lock debugging due to kernel taint

    Segmentation fault

The proc_create_single_data() conversion does not work because
single_open(file, nubus_proc_rsrc_show, PDE_DATA(inode)) is not
equivalent to the original code.

The Linux kernel CVE team has assigned CVE-2023-53217 to this issue.


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

	Issue introduced in 4.18 with commit 3f3942aca6da351a12543aa776467791b63b3a78 and fixed in 5.10.188 with commit f70407e8e0272e00d133c5e039168ff1bae6bcac
	Issue introduced in 4.18 with commit 3f3942aca6da351a12543aa776467791b63b3a78 and fixed in 5.15.120 with commit c06edf13f4cf7f9e8ff4bc6f7e951e4f074dc105
	Issue introduced in 4.18 with commit 3f3942aca6da351a12543aa776467791b63b3a78 and fixed in 6.1.38 with commit 67e3b5230cefed1eca470c460a2035f02986cebb
	Issue introduced in 4.18 with commit 3f3942aca6da351a12543aa776467791b63b3a78 and fixed in 6.3.12 with commit 9877533e1401dbbb2c7da8badda05d196aa07623
	Issue introduced in 4.18 with commit 3f3942aca6da351a12543aa776467791b63b3a78 and fixed in 6.4.2 with commit a03f2f4bd49030f57849227be9ba38a3eb1edb61
	Issue introduced in 4.18 with commit 3f3942aca6da351a12543aa776467791b63b3a78 and fixed in 6.5 with commit 0e96647cff9224db564a1cee6efccb13dbe11ee2

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-2023-53217
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:
	drivers/nubus/proc.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/f70407e8e0272e00d133c5e039168ff1bae6bcac
	https://git.kernel.org/stable/c/c06edf13f4cf7f9e8ff4bc6f7e951e4f074dc105
	https://git.kernel.org/stable/c/67e3b5230cefed1eca470c460a2035f02986cebb
	https://git.kernel.org/stable/c/9877533e1401dbbb2c7da8badda05d196aa07623
	https://git.kernel.org/stable/c/a03f2f4bd49030f57849227be9ba38a3eb1edb61
	https://git.kernel.org/stable/c/0e96647cff9224db564a1cee6efccb13dbe11ee2