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.
Metrics
Affected Vendors & Products
References
History
No history.
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Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2024-12-19T07:38:51.976Z
Reserved: 2024-05-21T13:27:52.128Z
Link: CVE-2021-47282
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Updated: 2024-08-04T05:32:08.008Z
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Status : Awaiting Analysis
Published: 2024-05-21T15:15:16.430
Modified: 2024-11-21T06:35:47.563
Link: CVE-2021-47282
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