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Message-ID: <2025123020-CVE-2023-54170-f1c6@gregkh>
Date: Tue, 30 Dec 2025 13:09:38 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2023-54170: keys: Fix linking a duplicate key to a keyring's assoc_array
From: Greg Kroah-Hartman <gregkh@...nel.org>
Description
===========
In the Linux kernel, the following vulnerability has been resolved:
keys: Fix linking a duplicate key to a keyring's assoc_array
When making a DNS query inside the kernel using dns_query(), the request
code can in rare cases end up creating a duplicate index key in the
assoc_array of the destination keyring. It is eventually found by
a BUG_ON() check in the assoc_array implementation and results in
a crash.
Example report:
[2158499.700025] kernel BUG at ../lib/assoc_array.c:652!
[2158499.700039] invalid opcode: 0000 [#1] SMP PTI
[2158499.700065] CPU: 3 PID: 31985 Comm: kworker/3:1 Kdump: loaded Not tainted 5.3.18-150300.59.90-default #1 SLE15-SP3
[2158499.700096] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 11/12/2020
[2158499.700351] Workqueue: cifsiod cifs_resolve_server [cifs]
[2158499.700380] RIP: 0010:assoc_array_insert+0x85f/0xa40
[2158499.700401] Code: ff 74 2b 48 8b 3b 49 8b 45 18 4c 89 e6 48 83 e7 fe e8 95 ec 74 00 3b 45 88 7d db 85 c0 79 d4 0f 0b 0f 0b 0f 0b e8 41 f2 be ff <0f> 0b 0f 0b 81 7d 88 ff ff ff 7f 4c 89 eb 4c 8b ad 58 ff ff ff 0f
[2158499.700448] RSP: 0018:ffffc0bd6187faf0 EFLAGS: 00010282
[2158499.700470] RAX: ffff9f1ea7da2fe8 RBX: ffff9f1ea7da2fc1 RCX: 0000000000000005
[2158499.700492] RDX: 0000000000000000 RSI: 0000000000000005 RDI: 0000000000000000
[2158499.700515] RBP: ffffc0bd6187fbb0 R08: ffff9f185faf1100 R09: 0000000000000000
[2158499.700538] R10: ffff9f1ea7da2cc0 R11: 000000005ed8cec8 R12: ffffc0bd6187fc28
[2158499.700561] R13: ffff9f15feb8d000 R14: ffff9f1ea7da2fc0 R15: ffff9f168dc0d740
[2158499.700585] FS: 0000000000000000(0000) GS:ffff9f185fac0000(0000) knlGS:0000000000000000
[2158499.700610] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[2158499.700630] CR2: 00007fdd94fca238 CR3: 0000000809d8c006 CR4: 00000000003706e0
[2158499.700702] Call Trace:
[2158499.700741] ? key_alloc+0x447/0x4b0
[2158499.700768] ? __key_link_begin+0x43/0xa0
[2158499.700790] __key_link_begin+0x43/0xa0
[2158499.700814] request_key_and_link+0x2c7/0x730
[2158499.700847] ? dns_resolver_read+0x20/0x20 [dns_resolver]
[2158499.700873] ? key_default_cmp+0x20/0x20
[2158499.700898] request_key_tag+0x43/0xa0
[2158499.700926] dns_query+0x114/0x2ca [dns_resolver]
[2158499.701127] dns_resolve_server_name_to_ip+0x194/0x310 [cifs]
[2158499.701164] ? scnprintf+0x49/0x90
[2158499.701190] ? __switch_to_asm+0x40/0x70
[2158499.701211] ? __switch_to_asm+0x34/0x70
[2158499.701405] reconn_set_ipaddr_from_hostname+0x81/0x2a0 [cifs]
[2158499.701603] cifs_resolve_server+0x4b/0xd0 [cifs]
[2158499.701632] process_one_work+0x1f8/0x3e0
[2158499.701658] worker_thread+0x2d/0x3f0
[2158499.701682] ? process_one_work+0x3e0/0x3e0
[2158499.701703] kthread+0x10d/0x130
[2158499.701723] ? kthread_park+0xb0/0xb0
[2158499.701746] ret_from_fork+0x1f/0x40
The situation occurs as follows:
* Some kernel facility invokes dns_query() to resolve a hostname, for
example, "abcdef". The function registers its global DNS resolver
cache as current->cred.thread_keyring and passes the query to
request_key_net() -> request_key_tag() -> request_key_and_link().
* Function request_key_and_link() creates a keyring_search_context
object. Its match_data.cmp method gets set via a call to
type->match_preparse() (resolves to dns_resolver_match_preparse()) to
dns_resolver_cmp().
* Function request_key_and_link() continues and invokes
search_process_keyrings_rcu() which returns that a given key was not
found. The control is then passed to request_key_and_link() ->
construct_alloc_key().
* Concurrently to that, a second task similarly makes a DNS query for
"abcdef." and its result gets inserted into the DNS resolver cache.
* Back on the first task, function construct_alloc_key() first runs
__key_link_begin() to determine an assoc_array_edit operation to
insert a new key. Index keys in the array are compared exactly as-is,
using keyring_compare_object(). The operation finds that "abcdef" is
not yet present in the destination keyring.
* Function construct_alloc_key() continues and checks if a given key is
already present on some keyring by again calling
search_process_keyrings_rcu(). This search is done using
dns_resolver_cmp() and "abcdef" gets matched with now present key
"abcdef.".
* The found key is linked on the destination keyring by calling
__key_link() and using the previously calculated assoc_array_edit
operation. This inserts the "abcdef." key in the array but creates
a duplicity because the same index key is already present.
Fix the problem by postponing __key_link_begin() in
construct_alloc_key() until an actual key which should be linked into
the destination keyring is determined.
[jarkko@...nel.org: added a fixes tag and cc to stable]
The Linux kernel CVE team has assigned CVE-2023-54170 to this issue.
Affected and fixed versions
===========================
Issue introduced in 5.3 with commit df593ee23e05cdda16c8c995e5818779431bb29f and fixed in 5.4.253 with commit 65bd66a794bfa059375ec834885bb610d75c0182
Issue introduced in 5.3 with commit df593ee23e05cdda16c8c995e5818779431bb29f and fixed in 5.10.188 with commit 0a6b0ca58685be34979236f83f2b322635b80b32
Issue introduced in 5.3 with commit df593ee23e05cdda16c8c995e5818779431bb29f and fixed in 5.15.123 with commit 9aecfebea24fe6071ace5cc9fd6d690b87276bbb
Issue introduced in 5.3 with commit df593ee23e05cdda16c8c995e5818779431bb29f and fixed in 6.1.42 with commit 00edfa6d4fe022942e2f2e6f3294ff13ef78b15c
Issue introduced in 5.3 with commit df593ee23e05cdda16c8c995e5818779431bb29f and fixed in 6.4.7 with commit e091bb55af9a930801f83df78195a908a76e1479
Issue introduced in 5.3 with commit df593ee23e05cdda16c8c995e5818779431bb29f and fixed in 6.5 with commit d55901522f96082a43b9842d34867363c0cdbac5
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-2023-54170
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:
security/keys/request_key.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/65bd66a794bfa059375ec834885bb610d75c0182
https://git.kernel.org/stable/c/0a6b0ca58685be34979236f83f2b322635b80b32
https://git.kernel.org/stable/c/9aecfebea24fe6071ace5cc9fd6d690b87276bbb
https://git.kernel.org/stable/c/00edfa6d4fe022942e2f2e6f3294ff13ef78b15c
https://git.kernel.org/stable/c/e091bb55af9a930801f83df78195a908a76e1479
https://git.kernel.org/stable/c/d55901522f96082a43b9842d34867363c0cdbac5
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