CVE-2023-54170
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 ---truncated---
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
A race condition in the Linux kernel's keyring subsystem can create duplicate an index key in the assoc_array, triggering a BUG_ON crash.
Vulnerability
Description
A race condition exists in the Linux kernel's keyring subsystem when linking a key into a keyring's associative array (assoc_array). Under rare timing conditions, the __key_link_begin and request_key_and_link functions can create a duplicate index key in the assoc_array, violating the data structure's invariants. This eventually triggers a BUG_ON check in assoc_array_insert at line 652 of lib/assoc_array.c, causing a kernel panic [1][2].
Exploitation
The vulnerability is triggered during DNS resolution performed by the kernel, specifically when dns_query() is called. The CIFS (Common Internet File System) client's cifs_resolve_server workqueue is a known trigger path, as shown in the crash report where the kernel panicked during a CIFS server resolution [1][2]. No special privileges are required beyond the ability to trigger a kernel DNS query, which can occur during normal filesystem operations.
Impact
An attacker who can cause the kernel to perform a DNS query under specific timing conditions can trigger a kernel crash (denial of service). The crash manifests as a BUG_ON in the assoc_array code, resulting in a system panic and potential data loss or service disruption. There is no evidence of memory corruption beyond the immediate crash, but the impact is a complete system denial of service [1][2].
Mitigation
The fix has been applied to the Linux kernel stable branches. The commit e091bb55af9a addresses the issue by ensuring proper synchronization in the key linking path to prevent duplicate index keys from being inserted into the assoc_array [1]. A second commit 00edfa6d4fe0 provides additional hardening [2]. Users should update their kernel to a version containing these fixes. No workaround is available for unpatched systems.
AI Insight generated on May 19, 2026. Synthesized from this CVE's description and the cited reference URLs; citations are validated against the source bundle.
Affected products
1- Range: <= 5.3.18-150300.59.90 (SLE15-SP3)
Patches
665bd66a794bf0a6b0ca586859aecfebea24f00edfa6d4fe0e091bb55af9ad55901522f96Vulnerability mechanics
Generated on May 9, 2026. Inputs: CWE entries + fix-commit diffs from this CVE's patches. Citations validated against bundle.
References
6- git.kernel.org/stable/c/00edfa6d4fe022942e2f2e6f3294ff13ef78b15cnvd
- git.kernel.org/stable/c/0a6b0ca58685be34979236f83f2b322635b80b32nvd
- git.kernel.org/stable/c/65bd66a794bfa059375ec834885bb610d75c0182nvd
- git.kernel.org/stable/c/9aecfebea24fe6071ace5cc9fd6d690b87276bbbnvd
- git.kernel.org/stable/c/d55901522f96082a43b9842d34867363c0cdbac5nvd
- git.kernel.org/stable/c/e091bb55af9a930801f83df78195a908a76e1479nvd
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