CVE-2021-47282
spi: bcm2835: Fix out-of-bounds access with more than 4 slaves
- Published
- Updated
- Reserved
- Assigned by
- Linux
Description
In the Linux kernel, the following vulnerability has been resolved: spi: bcm2835: Fix out-of-bounds access with more than 4 slaves Commit 571e31fa60b3 ("spi: bcm2835: Cache CS register value for ->prepare_message()") limited the number of slaves to 3 at compile-time. The limitation was necessitated by a statically-sized array prepare_cs[] in the driver private data which contains a per-slave register value. The commit sought to enforce the limitation at run-time by setting the controller's num_chipselect to 3: Slaves with a higher chipselect are rejected by spi_add_device(). However the commit neglected that num_chipselect only limits the number of *native* chipselects. If GPIO chipselects are specified in the device tree for more than 3 slaves, num_chipselect is silently raised by of_spi_get_gpio_numbers() and the result are out-of-bounds accesses to the statically-sized array prepare_cs[]. As a bandaid fix which is backportable to stable, raise the number of allowed slaves to 24 (which "ought to be enough for anybody"), enforce the limitation on slave ->setup and revert num_chipselect to 3 (which is the number of native chipselects supported by the controller). An upcoming for-next commit will allow an arbitrary number of slaves.
Timeline
ID reserved
By Linux
Published
- 2 years later
· 2 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| LinuxCNA (assigner) | 3.1 | High7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| NVDNVD · Modified | 3.1 | High7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 0.23% · top 86% of all CVEs (7 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.8.
Weakness
Affected products
- affected 571e31fa60b3697d5db26140e16d5c45c51c9815 – < b5502580cf958b094f3b69dfe4eece90eae01fbc
- affected 571e31fa60b3697d5db26140e16d5c45c51c9815 – < 82a8ffba54d31e97582051cb56ba1f988018681e
- affected 571e31fa60b3697d5db26140e16d5c45c51c9815 – < 01415ff85a24308059e06ca3e97fd7bf75648690
- affected 571e31fa60b3697d5db26140e16d5c45c51c9815 – < 13817d466eb8713a1ffd254f537402f091d48444
- affected 5.4
- unaffected < 5.4
- unaffected 5.4.126 – ≤ 5.4.*
- unaffected 5.10.44 – ≤ 5.10.*
- unaffected 5.12.11 – ≤ 5.12.*
- unaffected 5.13 – ≤ *
References (4)
- https://git.kernel.org/stable/c/b5502580cf958b094f3b69dfe4eece90eae01fbc (opens in a new tab)x_transferred
- https://git.kernel.org/stable/c/82a8ffba54d31e97582051cb56ba1f988018681e (opens in a new tab)x_transferred
- https://git.kernel.org/stable/c/01415ff85a24308059e06ca3e97fd7bf75648690 (opens in a new tab)x_transferred
- https://git.kernel.org/stable/c/13817d466eb8713a1ffd254f537402f091d48444 (opens in a new tab)x_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2021-47282)Record last updated .