CVE-2024-26807

In the Linux kernel, the following vulnerability has been resolved:

Both cadence-quadspi ->runtime_suspend() and ->runtime_resume() implementations start with:

struct cqspi_st *cqspi = dev_get_drvdata(dev);
struct spi_controller *host = dev_get_drvdata(dev);

This obviously cannot be correct, unless struct cqspi_st is the first member of struct spi_controller, or the other way around, but it is not the case. struct spi_controller is allocated by devm_spi_alloc_host(), which allocates an extra amount of memory for private data, used to store struct cqspi_st.

The ->probe() function of the cadence-quadspi driver then sets the device drvdata to store the address of the struct cqspi_st structure. Therefore:

struct cqspi_st *cqspi = dev_get_drvdata(dev);

is correct, but:

struct spi_controller *host = dev_get_drvdata(dev);

is not, as it makes host point not to a struct spi_controller but to the same struct cqspi_st structure as above.

This obviously leads to bad things (memory corruption, kernel crashes) directly during ->probe(), as ->probe() enables the device using PM runtime, leading the ->runtime_resume() hook being called, which in turns calls spi_controller_resume() with the wrong pointer.

This has at least been reported [0] to cause a kernel crash, but the exact behavior will depend on the memory contents.

[0] https://lore.kernel.org/all/20240226121803.5a7r5wkpbbowcxgx@dhruva/

This issue potentially affects all platforms that are currently using the cadence-quadspi driver.

Affected Software

References

• https://git.kernel.org/stable/c/03f1573c9587029730ca68503f5062105b122f61
• https://git.kernel.org/stable/c/32ce3bb57b6b402de2aec1012511e7ac4e7449dc
• https://git.kernel.org/stable/c/34e1d5c4407c78de0e3473e1fbf8fb74dbe66d03