Bug 2360936 (CVE-2025-40014)

Summary: CVE-2025-40014 kernel: objtool, spi: amd: Fix out-of-bounds stack access in amd_set_spi_freq()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: dfreiber, drow, jburrell, vkumar
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was discovered in the Linux kernel’s AMD SPI controller driver (amd_set_spi_freq()), which calculates a frequency index without validating its range when a very low clock rate is requested. If the requested frequency (speed_hz) is below the minimum supported value (AMD_SPI_MIN_HZ), the code may access beyond the end of an internal frequency table on the stack. A local, unprivileged user could trigger this issue to cause memory corruption, leading to a system crash or potentially exposing sensitive information. The fix limits the loop to valid entries, ensuring out-of-bounds access cannot occur.
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Description OSIDB Bzimport 2025-04-18 08:01:56 UTC 
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()
Comment 1 Avinash Hanwate 2025-04-18 12:27:16 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025041822-CVE-2025-40014-384f@gregkh/T