[SRU][N][PATCH 0/1] CVE-2025-40014

[Cengiz Can]

https://ubuntu.com/security/CVE-2025-40014

[ Impact ]

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

objtool, spi: amd: Fix out-of-bounds stack access in amd_set_spi_freq()

If speed_hz < AMD_SPI_MIN_HZ, amd_set_spi_freq() iterates over the entire
amd_spi_freq array without breaking out early, causing 'i' to go beyond the
array bounds.

Fix that by stopping the loop when it gets to the last entry, so the low
speed_hz value gets clamped up to AMD_SPI_MIN_HZ.

Fixes the following warning with an UBSAN kernel:

drivers/spi/spi-amd.o: error: objtool: amd_set_spi_freq() falls through to next
function amd_spi_set_opcode()

[ Fix ]

noble/linux: backported from 76e51db43fe4

[ Test Plan ]

Build and boot tested.

[ Where Problems Could Occur ]

A bad fix would affect systems using the AMD SPI controller driver
(drivers/spi/spi-amd.c), which is found on AMD platforms that expose an SPI
master through this driver. Since the change alters the frequency clamping
logic for the AMD_SPI_MIN_HZ lower bound, a regression could cause SPI
devices attached to that controller to be programmed at an incorrect clock
rate. Systems without AMD SPI hardware, or that do not use this driver, are
not affected by this change.

[ Other Info ]

Kybele flow-v11-25-ga27c0fa6. Reference: e0a0e79f/v1