Bug 2460648 (CVE-2026-31485)

Summary: CVE-2026-31485 kernel: spi: spi-fsl-lpspi: fix teardown order issue (UAF)
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the `spi-fsl-lpspi` driver within the Linux kernel. This vulnerability, identified as a Use-After-Free (UAF) issue, stems from a teardown order problem during the unregistration of the Serial Peripheral Interface (SPI) controller. When a running SPI transfer attempts to access deallocated memory during the synchronous teardown of Direct Memory Access (DMA) channels, it can lead to a NULL pointer dereference. This ultimately causes the system to crash, resulting in a Denial of Service (DoS).
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Description OSIDB Bzimport 2026-04-22 15:02:59 UTC 
In the Linux kernel, the following vulnerability has been resolved:

spi: spi-fsl-lpspi: fix teardown order issue (UAF)

There is a teardown order issue in the driver. The SPI controller is
registered using devm_spi_register_controller(), which delays
unregistration of the SPI controller until after the fsl_lpspi_remove()
function returns.

As the fsl_lpspi_remove() function synchronously tears down the DMA
channels, a running SPI transfer triggers the following NULL pointer
dereference due to use after free:

| fsl_lpspi 42550000.spi: I/O Error in DMA RX
| Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
[...]
| Call trace:
|  fsl_lpspi_dma_transfer+0x260/0x340 [spi_fsl_lpspi]
|  fsl_lpspi_transfer_one+0x198/0x448 [spi_fsl_lpspi]
|  spi_transfer_one_message+0x49c/0x7c8
|  __spi_pump_transfer_message+0x120/0x420
|  __spi_sync+0x2c4/0x520
|  spi_sync+0x34/0x60
|  spidev_message+0x20c/0x378 [spidev]
|  spidev_ioctl+0x398/0x750 [spidev]
[...]

Switch from devm_spi_register_controller() to spi_register_controller() in
fsl_lpspi_probe() and add the corresponding spi_unregister_controller() in
fsl_lpspi_remove().
Comment 1 Keith Grant 2026-04-22 18:49:06 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026042259-CVE-2026-31485-e15c@gregkh/T