CVE-2021-46959 - CVE House
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Status published High CVE-2021-46959

spi: Fix use-after-free with devm_spi_alloc_*

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: spi: Fix use-after-free with devm_spi_alloc_* We can't rely on the contents of the devres list during spi_unregister_controller(), as the list is already torn down at the time we perform devres_find() for devm_spi_release_controller. This causes devices registered with devm_spi_alloc_{master,slave}() to be mistakenly identified as legacy, non-devm managed devices and have their reference counters decremented below 0. ------------[ cut here ]------------ WARNING: CPU: 1 PID: 660 at lib/refcount.c:28 refcount_warn_saturate+0x108/0x174 [<b0396f04>] (refcount_warn_saturate) from [<b03c56a4>] (kobject_put+0x90/0x98) [<b03c5614>] (kobject_put) from [<b0447b4c>] (put_device+0x20/0x24) r4:b6700140 [<b0447b2c>] (put_device) from [<b07515e8>] (devm_spi_release_controller+0x3c/0x40) [<b07515ac>] (devm_spi_release_controller) from [<b045343c>] (release_nodes+0x84/0xc4) r5:b6700180 r4:b6700100 [<b04533b8>] (release_nodes) from [<b0454160>] (devres_release_all+0x5c/0x60) r8:b1638c54 r7:b117ad94 r6:b1638c10 r5:b117ad94 r4:b163dc10 [<b0454104>] (devres_release_all) from [<b044e41c>] (__device_release_driver+0x144/0x1ec) r5:b117ad94 r4:b163dc10 [<b044e2d8>] (__device_release_driver) from [<b044f70c>] (device_driver_detach+0x84/0xa0) r9:00000000 r8:00000000 r7:b117ad94 r6:b163dc54 r5:b1638c10 r4:b163dc10 [<b044f688>] (device_driver_detach) from [<b044d274>] (unbind_store+0xe4/0xf8) Instead, determine the devm allocation state as a flag on the controller which is guaranteed to be stable during cleanup.

Impact Analysis

Refer to official advisory for detailed impact metrics.

Remediation

Ensure systems are updated to the latest vendor-supplied patch levels.

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Credits & Attribution

No credits recorded in the NVD database.

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Affected Vendor

Affected Software

Linux
Vulnerable Versions:
a4add022c1552b0d51a0b89a4781919d6ebac4f9, 0870525cf94bc27907e94ce99afb6d7239ffd2f5, 8c45a1c6c951bbe7f95db78fcab46f7337364468, 234b432c7b6184b2d6c5ba2c55f0dd5023c0edf0, 3e04a4976addbedcad326f47b0dd4efc570a1fac, 5e844cc37a5cbaa460e68f9a989d321d63088a89, bd1a5b2307279029faaddbecf2f2ac25eaef8dc6, 4.4.248, 4.9.248, 4.14.212, 4.19.163, 5.4.80, 5.9.11, 5.10, 0, 4.4.271, 4.9.271, 4.14.233, 4.19.191, 5.4.119, 5.10.37, 5.11.21, 5.12.4, 5.13

Timeline

Official Publish: February 29th, 2024
Last Modified: May 23rd, 2026
Added to House: July 21st, 2026

CVSS Vectors

V3: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Weaknesses (CWE)

No CWE data available

MITRE ATT&CK TTPs

No associated TTPs found for this vulnerability.