# CVE-2021-46959: linux: In the Linux kernel, the following vulnerability has been resolved:  spi: Fix use-after-free with devm_spi_alloc_*  W...

CVE-2021-46959 is fixed in linux on 1 platform, first by DEBIAN-CVE-2021-46959, released February 29, 2024. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2021-46959
- Priority: High
- CVSS: 7.8 (high)
- EPSS: 0.0025
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Feb 29, 2024

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 5.10.38-1 | [DEBIAN-CVE-2021-46959](https://patchblox.com/security/data/fix/linux/debian-cve-2021-46959.md) | Feb 29, 2024 |
| Linux | linux Debian 13.5 (trixie) | 5.10.38-1 | [DEBIAN-CVE-2021-46959](https://patchblox.com/security/data/fix/linux/debian-cve-2021-46959.md) | Feb 29, 2024 |
| Linux | linux Debian 14 | 5.10.38-1 | [DEBIAN-CVE-2021-46959](https://patchblox.com/security/data/fix/linux/debian-cve-2021-46959.md) | Feb 29, 2024 |

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