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CVE-2026-90012
spi: Fix DMA mapping ownership on partial map failure
Published 2026-09-16 (33 days ago) by the Linux kernel CNA. Subsystem drivers/spi. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-90012 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | not affected | 6.1.190-1 | Nothing to do. bookworm never shipped the vulnerable code. |
| Debian 13trixie | fixedDSA-6528-1 · 2026-09-29 · text | 6.12.111-1 | Update the kernel and reboot. DSA-6528-1 shipped the fix on 2026-09-29, in 6.12.111-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4817-1 · 2026-10-04 · text | 6.12.111-1~deb12u1 | Update the kernel and reboot. DLA-4817-1 shipped the fix on 2026-10-04, in 6.12.111-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
If RX mapping fails after TX mapping succeeds, __spi_map_msg() unmaps TX but leaves tx_sg_mapped set. If TX mapping fails on a later transfer, mappings created for earlier transfers remain active. In both cases, cur_{tx,rx}_dma_dev have not yet been updated because they are assigned only after every transfer has been mapped. The subsequent spi_unmap_msg() may therefore unmap the TX mapping again or release earlier mappings using a NULL or stale device. Using a NULL device can trigger an oops. An empty SG table does not prevent the NULL dereference because dma_unmap_sg_attrs() accesses the device before checking the entry count. Publish both mapping devices before mapping starts and unwind all failures through __spi_unmap_msg(). This clears the mapping flags and releases each mapping once with the device that created it. Publishing the devices before the loop also refreshes them when no transfer needs mapping. No mapping flag is set in that case, so current users do not use the pointers as mapping owners.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
drivers/spi/spi.c
- What this is
- SPI SUBSYSTEMMAINTAINERS section matched on drivers/spi/ · linux-spi@vger.kernel.org · Maintained
Check it on the machine
grep -wE 'CONFIG_SPI|CONFIG_SPI_MASTER' /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
Show whether Debian builds this, per release
Debian builds this, but not on every flavour. At least one release below builds the code on some of its kernel flavours and not on others, so the answer depends on the architecture and flavour installed.
- bookworm, trixie, forky, sid, bookworm · linux-6.12Ynot built on amd64/cloud-amd64, arm64/cloud-arm64
- Y
- built in where it is built at all; some flavours do not build it
- Build switches
- CONFIG_SPI, CONFIG_SPI_MASTER
- Reads as
- all on means the file is compiled; any one off means it is not.
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-09-16 (33 days ago)source
- CVSS
- 9.8 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.63%, higher than 48.9% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- drivers/spi
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.11 | 6.12.110 | cc8354213ad6 |
| 6.11 | 6.18.51 | a38051fa2dde |
| 6.11 | 7.2.5 | 5def8b6aaad4 |
| 6.11 | 7.3 | 367cea239fc9 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4817-1 | 2026-10-04 | bookworm 6.12.111-1~deb12u1 | tracker |
| DSA-6528-1 | 2026-09-29 | trixie 6.12.111-1 | tracker |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:NAttack vector, network
- Unauthenticated frames to a network-facing SPI NIC such as ENC28J60 or W5500 cause the driver to call spi_sync() with a multi-transfer command-plus-payload message, which reaches __spi_map_msg() in the SPI core with no local login.
- AC:LAttack complexity, low
- The attacker decides when transfers run (packet flood) and can force a partial DMA map failure via memory or IOMMU pressure; controllers such as fsl-lpspi DMA-map even tiny transfers and MUST_TX/MUST_RX dummy buffers create the TX-then-RX failure the bug requires, with no race to win.
- PR:NPrivileges required, none
- The SPI Ethernet receive and transmit paths run before any protocol authentication and have no capability, device-node, or namespace check, so a remote sender needs no privileges.
- UI:NUser interaction, none
- Once the SPI NIC is configured and up, attacker traffic alone drives spi_sync() into the mapping path; no separate victim action is required.
- S:UScope, unchanged
- Wrong-device or double DMA unmap and the resulting oops stay inside the host kernel DMA/IOMMU authority and do not cross a VM, guest, or other authorization boundary.
- C:HConfidentiality impact, high
- On partial map failure the core leaves tx_sg_mapped set after unmapping TX, or leaves earlier live mappings active, then spi_unmap_msg() unmaps again with a NULL or stale DMA device, corrupting IOMMU bookkeeping in a way that can expose kernel memory.
- I:HIntegrity impact, high
- Double-unmap or wrong-device unmap of scatter-gather DMA mappings can alias or tear down IOVAs and allow writes into unintended kernel memory, so integrity impact is high under the required higher-severity rule.
- A:HAvailability impact, high
- dma_unmap_sg_attrs() loads the mapping device before checking the SG entry count, so a NULL cur_{tx,rx}_dma_dev (or a NULL sgl on the IOMMU unmap path) causes a repeatable kernel oops.