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CVE-2026-89994
dmaengine: fsl-edma: tracing: no ptr dereference during log output
Published 2026-09-16 (33 days ago) by the Linux kernel CNA. Subsystem drivers/dma. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-89994 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
The fsl edma events store a pointer to a struct fsl_edma_engine in the ringbuffer and dereference it when a log entry is printed. At this time, the pointer may no longer be valid. Event injection can be used to trigger a crash: $ cd /sys/kernel/tracing $ echo 'value = 0' > events/fsl_edma/edma_writeb/inject $ cat trace The log output needs only edma->membase. Add a membase field at the end of the event and use the new field for log output. Keep the existing fields for backward compatibility.
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/dma/fsl-edma-trace.h
- What this is
- FREESCALE eDMA DRIVERMAINTAINERS section matched on drivers/dma/fsl-edma*.* · imx@lists.linux.dev · Maintained
Show whether Debian builds this, per release
Not established. This site could not find the build rule for the affected file in the kernel trees Debian ships, so it has no answer about whether Debian compiles this code. Read that as unknown, never as absent.
- bookworm, trixie, forky, sid, bookworm · linux-6.12?
- ?
- not established - no Makefile entry for the affected file
Where a release above reads "not established", no build rule for the affected file was found in that release's kernel tree. That is a gap in this lookup, not a finding that the code is absent.
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
Signals
- Published
- 2026-09-16 (33 days ago)source
- CVSS
- 7.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.20%, higher than 8.9% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- drivers/dma
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.10 | 6.12.110 | ef02cd3807f3 |
| 6.10 | 6.18.51 | d382aaf5fed3 |
| 6.10 | 7.2.5 | 2a3801ae5c34 |
| 6.10 | 7.3 | 2ea04dca8e62 |
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:LAttack vector, local
- The stale dereference runs only when a local actor reads formatted fsl_edma events from tracefs (/sys/kernel/tracing/trace or trace_pipe). DMA MMIO tracing and event injection only enqueue ring-buffer records; there is no network, adjacent-radio, or physical-device path into TP_printk().
- AC:LAttack complexity, low
- An attacker with tracefs access controls the full sequence: enable edma_log_io events, either inject a record via events/fsl_edma/*/inject or generate eDMA I/O then unbind/remove fsl-edma so the stored engine pointer is freed, then read trace. No race or uninfluenced victim state is required.
- PR:LPrivileges required, low
- tracing_check_open_get_tr() enforces only LOCKDOWN_TRACEFS and DAC, with no capable() check. Event enable and trace files are mode 0640 and are routinely delegated via tracefs gid= to tracing-group members on Android Automotive/NXP i.MX, ChromeOS, and developer kernels, matching prior TP_printk UAF CVEs.
- UI:NUser interaction, none
- No victim interaction is required. The attacker enables fsl_edma events, injects or records a stale edma pointer, and reads the formatted trace themselves to invoke the vulnerable TP_printk() path.
- S:UScope, unchanged
- Impact stays inside the host kernel's trace formatting path (stale fsl_edma_engine dereference). This is standard local kernel memory-safety impact with no VM escape, IOMMU/DMA boundary bypass, or other cross-authority effect; membase is used only for log offset arithmetic.
- C:HConfidentiality impact, high
- TP_printk() dereferences __entry->edma->membase when formatting output. That is a use-after-free read of a freed fsl_edma_engine, and with event injection the edma field is attacker-chosen, yielding an arbitrary kernel pointer read whose result is printed as the register offset.
- I:HIntegrity impact, high
- The bug is a use-after-free of the kernel heap object fsl_edma_engine, which embeds dma_device function pointers. Freed memory can be reclaimed before the trace read, enabling heap grooming and write/control-flow primitives; kernel CNA guidance rates UAF integrity impact as High.
- A:HAvailability impact, high
- Dereferencing a NULL (inject with a zeroed edma pointer) or freed fsl_edma_engine pointer during trace formatting causes a kernel oops or panic. The fix commit demonstrates a deterministic crash via inject followed by cat trace.